Riddle: will you Get it In a Blue moon?

Who am I?

I am not valid in any language but can be found in the dictionary.
You can't say me and you can't understand me.
A doctor cannot help you but doctor is something that should give you a start.

I can be QWERTY and ASDFGH.
It is me if you try to write riddle and really write drdlei.
I am in this post.

So I am asking you: Who am I?

Okay, I am giving you a hint:

Hint 1:

If your reputation is a bug, you can remove me from posts, here at SE.

And I give you an other hint, I already gave in the comments:

Hint 2: (I changed something)

• Is it something to do with Spoonerism? – Mea Culpa Nay Jan 3 '18 at 17:44
• @MeaCulpaNay It is the right direction, but it is not Spoonerism. – MEE the sneaky user Jan 3 '18 at 19:33

Are you...

gibberish?

"I am not valid in any language but can be found in the dictionary."

noun, unintelligible or meaningless speech or writing; nonsense.

"You can't say me and you can't understand me."

Written gibberish is likely unpronounceable and spoken gibberish is not understandable.

"A doctor cannot help you but doctor is something that should give you a start."

Because a doctor's handwriting is often messy and unintelligible?

"I can be QWERTY and ASDFGH."

These are often used as meaningless text gibberish (such as for a string value in a programming example) since they just represent pressing sequential keys from left to right on a row of a QWERTY keyboard. As Chris points out, QWERTY isn't technically gibberish, since it has a meaning.

"It is me if you try to write riddle and really write drdlei."

A sample of gibberish.

"I am in this post."

Yes. ;)

Hint 1:

If you're bothered by your low rep, you can edit the gibberish out of questions to earn some.

Hint 2:

The only capital letters in the title are "GIB", the start to the word.

• Good answer, but "you can't say me" doesn't seem to fit at all, at least not the way you have described your answer. – Jay Jan 4 '18 at 5:19
• Hey, this is the correct answer. Although I thought something different with A doctor cannot help you but doctor is something that should give you a start.: The word doctor is a title and there was a hint in the title, and with hint1 I thought of the millenium (Y2K) bug, and the editing privilege starts at 2K rep here at puzzling.SE – MEE the sneaky user Jan 4 '18 at 6:42
• QWERTY isn't really gibberish. It is a perfectly valid word in common usage (cf dictionary.cambridge.org/dictionary/english/qwerty ) so I'm not sure that line works (though it may be what the OP had in mind) – Chris Jan 4 '18 at 10:58
• @Chris, oh, didn't knew that ... – MEE the sneaky user Jan 4 '18 at 14:54

You might be ...

I am not valid in any language but can be found in the dictionary.


The up-arrow or shift symbol is not a word in any language, but shifted (capitalized) letters are found in dictionaries, as is the word "shift".

You can't say me and you can't understand me.


The symbol is not something you can pronounce, nor get any real meaning from when it's all by itself.

A doctor cannot help you but doctor is something that should give you a start.


The title "Doctor" (or "M.D.") needs a shift key to type.

I can be QWERTY and ASDFGH.


Yup, those are shifted (capitalized) letters.

It is me if you try to write riddle and really write drdlei.


Yup, those letters have shifted around.

I am in this post.


Yup.

Hint 1:

If your reputation is a bug, you can remove me from posts, here at SE.
You can remove the up-arrow (up-votes) on posts.

Hint 2:

The title is a BIG hint to start with.
BIG letters at the starts of some of the words in the title, suggest shifted (capitalized) letters.

• Good idea, too, but not correct – MEE the sneaky user Jan 4 '18 at 6:44
• That 'doctor explanation' was really forced... – Tyler Jan 4 '18 at 10:56

Are you a

nonce?

I am not valid in any language [...]

Nonces are not part of a standard language by definition

[...] but can be found in the dictionary.

The word nonce is in the dictionary. Or it could be a reference to nonces that become full-fledged words.

You can't say me and you can't understand me.

Nonces often don't have an identifiable meaning. Written nonces often don't have an obvious pronunciation.

A doctor cannot help you but doctor is something that should give you a start.

??

I can be QWERTY and ASDFGH.

Examples of nonces.

It is me if you try to write riddle and really write drdlei.

drdlei is a nonce

I am in this post.

drdlei and ASDFGH

• Very close, but not the solution. – MEE the sneaky user Jan 3 '18 at 20:07
• I added a hint. – MEE the sneaky user Jan 3 '18 at 20:11
• Pity, that sounded good, especially, because (n)once in a blue moon could have been the meaning of the title. – M Oehm Jan 3 '18 at 20:13
• Yes, that would have been a good idea, too, but look at the title, maybe I hid an other message in it ... – MEE the sneaky user Jan 3 '18 at 20:15

Colon (:)

Reasoning:

I am not valid in any language but can be found in the dictionary.

The colon isn't in any word in the dictionary, but the word "colon" is in the dictionary.

You can't say me and you can't understand me.

The colon symbol itself isn't pronouncable? Admittedly, this one's a bit of a stretch.

A doctor cannot help you but doctor is something that should give you a start.

I can be QWERTY and ASDFGH.

No idea.

It is me if you try to write riddle and really write drdlei.

Super stretching on this one, but colons usually precede lists in text. Lists can be ordered or unordered, like the words riddle and drdlei.

I am in this post.

So I am asking you(:) Who am I?

• Good idea, but not the solution (wrong direction) – MEE the sneaky user Jan 3 '18 at 19:48
• I added a hint. – MEE the sneaky user Jan 3 '18 at 20:11

I think it's

Anagrams

I am not valid in any language but can be found in the dictionary:

Most anagrams are not valid words, but the word "anagram" itself is in the dictionary.

You can't say me and you can't understand me:

Anagrams are really hard to pronounce and understand. Try pronouncing "aaarngm".

A doctor cannot help you but doctor is something that should give you a start:

I can be QWERTY and ASDFGH:

"QWERTY" and "ASDFGH" could be anagrams of some word. (I tried solving them but couldn't so this line may just be stating that anagrams are weird looking words)

It is me if you try to write riddle and really write drdlei

Dah! "drdlei" is an anagram of "riddle".

I am in this post:

There are two:
1. In the title, the uppercased letters are "GIB", which is an anagram of "BIG".
2. There is an anagram of "riddle".

Hint 1:

404

Hint 2:

In the title, the uppercased letters are "GIB", which is an anagram of "BIG". (lazily copy-pasted)

• That is a great idea, too, but not the correct one. – MEE the sneaky user Jan 4 '18 at 6:45

My Guess is

"Typo" ? Related with Keyboard and to write riddle and really write drdlei is a typo.

• This could fit, too, but is nor the original answer – MEE the sneaky user Jan 4 '18 at 6:45

Closely related to @Vikalp's answer, but I think it's

misprint

• This could fit, too, but is nor the original answer – MEE the sneaky user Jan 4 '18 at 6:45

Are you:

an initialism?

I am not valid in any language but can be found in the dictionary.

Initialisms aren't words in any language but some initialisms are defined in the dictionary

You can't say me and you can't understand me.

Initialisms aren't pronounced as words but as each letter in turn. Nor do they have meaning as a word.

A doctor cannot help you but doctor is something that should give you a start.

'Doctor'-> 'M.D' = initialism

I can be QWERTY and ASDFGH.

Hmm. These can be initialisms? QWERTY is sort of an acronym

It is me if you try to write riddle and really write drdlei.

As could be this

I am in this post.

See above

Hint 1:

Presumably you can replace these with what they stand for to clarify posts if your rep is 2,000+ (year of the millennium bug)

• Hey, this is a great solution. You also found some solutions, the accepted one did not found, ... – MEE the sneaky user Jan 4 '18 at 6:44