Friends!
Is there any option in Gmail that we can change our primary Email address?

No. once created you must keep it or delete it and use another id, maybe something similar.

No, my friend its happen with my friend ,she told me somebody add her and after that day whenever she used her that gmail id n pswrd , her email shoed another one thats not her own.

and via teamviewer I have also seen same thing on her pc. I don't knw howz it happend but Its true that her primary email address is changed from settings , now I wana again change her settings and wana give her back her old ID which she used but no body can see her real ID.

Its also strange for me and I need your help can anybody help me in this regards. Is there any option in gmail settings from where I again change her ID. and can remove that boyish ID. which is stick with her.

When your in Gmail at the very top right you will see this after the e-mail address 1st the labs picture (the thing looks like a green bottle) | Settings | Help | Sign out....then click on settings then you will see this General
Accounts and Import
Labels
Filters
Forwarding and POP/IMAP
Chat
Web Clips
Labs
Themes, click on Accounts and Import, then look for send mail as, you can ,make your changes there, add a letter or a number and then mail new address to all contacks, its a little bit of a hassle but workable, good luck!