If you're seeing a "GAH Error 1111" message when signing in to AOL Mail, there are a couple quick fixes you can try to get you back in to your account.
Change your password:
The easiest way to fix this problem is to change your AOL password. Once you've reset the password, make sure you sign in again at mail.aol.com.
Clear your cache and cookies:
If you're still unable to access your mail after resetting the password and signing in from the mail site, you'll need to clear your browser's cache and cookies. Once you've cleared your browser, make sure you close and restart it before trying to sign in at mail.aol.com again.