Registry

I think my registry files for FS9 have gone because I can't use FS9 in my username on XP, but I can use it on my sisters! how can I fix this? I've tried re-installing but it didn't work. Please help I'm desperate!!
Flight Simulator and other chat
https://forums.simviation.com/phpBB3/
https://forums.simviation.com/phpBB3/viewtopic.php?f=20&t=50346
it was my dad who did it, He installed a game on it then it didnt work, so he did a system restore, now I can't access FS9 on my username??? when I start my computer up when it comes to the page where you click on your username it comes up with something about "one or more of the systems registry files has been deleted"??????????????????