- My prefix is case closed.
- My suffix has only one.
- My infix is not closed.
- My whole is no one.
2 Answers
My prefix is case closed.
Z, the last letter, case closed.
My suffix has only one.
O for only and for one (the first letter of each of those words).
My infix is not closed.
An ER, emergency room, should always be open to customers.
My whole is no one.
ZERO is not one.
ALONE
My prefix is case closed.
A, the first letter, case closed.
My suffix has only one.
ONE is literally only "one".
My infix is not closed.
When you don't close the lights they are ON.
My whole is no one.
ALONE means no one else with you.