I had live ID with "gmail.com" in the end, and changed that to live.com alias. All services updated to the new liveID name(its unique identifier stays the same). But the phone for now is trying to use old email with "gmail" to access liveID features. Is there a way to change it without HARD RESETTING the phone(actually its same old LiveID with different name). My phone is developer unlocked. May be there is some way to do that "not with tools provided officially"
The official way to change the Windows Live ID associated with your phone is only with a reset. In your case, the Unique ID (which is a number associated with every Windows Live ID) is the same and you've changed only the Widows Live ID (which is an e-mail address). Even so, this email account cannot be changed on the Windows Phone since the first Live email account you set up and synchronize with the device cannot be deleted or changed. There's been a request put up to change this.