Is it correct to say i am she?

Answer 1

Yes. The predicate nominative "she" follows the copula ( "linking verb") am. Many people will say " I am her" but it is incorrect because her is an object form, not a predicate nominative, and thus cannot be linked to the subject "I" through the copula.

Answer 2

You could say:

1. I don't know who she is.
2. I don't know! Who is she?

Answer 3

"I don't know where she is" would be more proper.