For Some Reason On My HTC wildfire i can no longer go on the market place or google mail is says 'You entered the wrong password or your account has changed. please re-enter your password

username 19li91am @ youtube.com'

its not just me with this problem i looked in the android forums and many people are having this problem where for some reason the login emails have changed, my email should be liamfarr15 @ hotmail.com but it changed to that one which i can not even remember making. anyone have a solution for this?

Thanks.