Can't open any .exe file or Regedit.

Hello,

Like the title says I am having trouble opening .exe files. Now I was following another answer from here that said I should copy regedit onto the desktop and change it into a .COM file to open it. After doing all of that it still does not open. I get the warning message and click ok, but nothing happens after doing this. This happened to my other computer a couple days, and I can't fix it. I could really use some help please.