What to do if you get scammed, and how to get an account back
1. Go to forgot password. Enter your birthday and security password, then reset your password. You cannot get your account back if you forgot the Date of Birth and security answer you used!
2. Check your mailbox if that doesn't work, it means he changed the ID, and the new ID is in your mailbox.
Call Sony support at 1-800-345-SONY(7669) and attempt to have them restore your e-mail address and e-mail you a temporary password. If you cannot give them enough information, they cannot help you. Advice: don't mention gamesharing!
They will probably help you as you are a + member.