Login gmail account

Point your web browser at http://www.gmail.com

If another account comes up, sign out of it by clicking the avatar in the upper-right then clicking "Sign out."

Be sure to sign out of your account when you're done.

Maybe, try setting-up a second Gmail account, then send transfer) your emails from the old username account to the new username account. If this works, then either try deleting the messages from the old gmail account and transfer the messages from the new gmail account back to the original gmail account ... or ... just delete the old gmail account if you successfully transferred them to the new gmail account.

please sign in / sign up using computer first time and use mobile data internet packet (2G/3G) with desired SIM provider and download / surf for gmail .com / gmail login app in android then login to ur account using same password and user id that you logged on through computer and now you can create / set up new account

If you can login to your Gmail account, click your avatar in the upper-right, click "Account" (on the same line as "Privacy"), click "Security" on the left, then click "Change password" at the top of the body.

If you can't login to your Gmail account, click the "Can't access your account?" link on the Gmail sign-in page.

This page will show you a few ways you can login to gmail with multiple accounts. Check this out

http://www.xinz.org/mobile/multiple-gmail-sign-in-gmail-login/

first you log out from your gmail account and then try to login the gtalk .
After this you can login the gmail account. By this method you connect to the Google Talk service.

Menu>Messages>>>Email>>Settings>>New Account>> Add>> Account name>> Connect using>>(Chose your ISP)>>enter email address>>select Connection type as POP3>>incoming server address for the mail you want to configure (ex yahoo= pop.mail.yahoo.com, google: pop.gmail.com) username: (yahoo or gmail login id)..>> Password( for you account)..>> outgoing server (yahoo : smtp.mail.yahoo.com or for gmail: smtp.gmail.com) please specify your login credentials again, then port number is 110 and 25. should work.