My Windows 7 computer will not let me open any programs?

Hello. Lately I experienced some problems with my Registry Editor and my file extensions such as .exe and .ink. A friend of mine who works in IT tried to help but he hasn't had the time to research the problem. I tried to fix it myself and I think I might have messed up something in Registry Editor. When I go to my desktop, all of my program's icons are blank,white pages. When I click on them nothing happens. Some of them say," Application not found." I made a system restore point about a month ago and I was going to use that but when I search for it in Start, it won't even bring it up. I've tried starting CMD in Task Manager and typing in the file name for System Restore but it won't even bring that up. Nor will it bring up my Registry Editor if I might somehow be able to fix the problem through that. I tried starting the computer in Safe Mode, then using Command Prompt, but that does nothing either. I can't even open my antivirus software. The only reason I was able to send this question is because I'm using my iPad. I really need some help. Someone has got to know what's going on.