I had the same problem and practically NOTHING worked for me. I couldn't get into cmd or regedit because everything was .exe and I couldn't open any of it. Nor could I download anything because of this.
This was the solution that worked for me. I thought I'd share it.
first you create a new notepad file in another PC (or u right click --- new --- notepad and the open it)
copy and paste this on the notepad file:
Windows Registry Editor Version 5.00
now click file---save us
change the File type to (All files (*.*))
change the encoding to (unicode)
put in the file name (exe.reg)
save it in the desktop
now go to the desktop you will find a file named (exe) with a registry icon
double click it ----yes--- yes
restart your PC