I can't open any .exe files

I can't open any .exe files other
than explorer, all of my icons in the program list and
desktop have an iexplorer icon. It seems that my file
types are messed up. I also get the message "Windows
cannot open this file"(needs to know what created
program) when I try to open anything, including system
restore, msconfig, regedit, etc.

Any ideas? what could be causing this in the first place?

So far I've received following advice, but have not had a
chance to try it yet:

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For starters check to see if the drive letter these
programs are located on has changed (for example drive C
is now D in My Computer. Navigate directly to the program
you want to run and open it insted of using the shortcut
and see if it opens that way. For example to open
regedit: Go to My Computer and navigate here
C:\WINDOWS\regedit
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