Deleted Registry Entry, Now Users Messed Up

I have Windows 7, 64 bit, Home.

I was trying to uninstall a program and deleted a registry entry that appeared related to the program, but clearly was not. The registry entry, if it matters, was at:

HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Windows NT > Current Version > ProfileList > S-14 - a bunch of numbers

What happened next was a bit surprising. When I rebooted my computers (to check the effects of the registry changes), Windows 7 looked like it had when Windows 7 was first installed. The wallpaper was the default, all of the settings were the original ones and every other change that I made to the OS was reverted to default. This included program settings, like Firefox addons and settings for other programs. The hard drive was fine, all of the programs are still there, just the settings gone.

I went to check the Users folder, and I noticed a new user was created, automatically by Windows. My old username is still there (let's called it User1), along with a new, active username (User2).

I can't change users to User1 by logging off. However, everything still seems to be there in the folder. User2 seems to be active.

Now, my question.

How do I get back to using User1? Can I import all of the settings? Is there a way to do this? Can I change some registry entries? Make a new one? I dunno...