Your profile is probably not gone... you need to login as local administrator and look in the C:\Documents and Settings directory. You should see a directory with your old login. All of your stuff is in there.
We have had this happen in the past, if your profile is locked when you try to login, it will default to that one.
If you want a simple check, try logging off and logging in with your old ID? It might be that simple. Of course, you need to find out what had the profile locked and I would definitely do a backup if you haven't recently.