Can't Access Missing Files

A couple of days ago I stupidly opened a reg file which ended up slowly destroying my computer. THe first sign was applications taking longer to open. It would come up with 'Application error' then after pressing ok, I opened it again and it opened with success. It also took me a couple of goes to open the Task manager as well. The next thing I noticed was sometimes, explorer.exe wouldn't open so I would have to manually type it in via Task manager. Once Task Manager was opened, I would notice hundereds of drwatson's, which I had to end task. Now it seems my Laptop is working fine, however, there's a problem. It says all my files are there, but I can only access the program file ones (and even most of them don't open). All the main files, which were located in My Documents, I can't access. I'm on a new account Windows XP made, but the old account is still there, however, when I go to Control Panel, only my new account appears, not the old one. I go to Documents And Settings and the folder is there, however, it says it's empty. When I double click it, an error pops up saying, 'Access is denied.' I know all my files are there because I have 50 GB's of space and I only have 10 GB's free space remaining. I highlighted all the files (excluding My documents) and it came to a total of 10 GB's only. There's still that extra 30 I had located in My documents.