How to recover "Open With" option of exe files on Windows XP

Accidentally or purposely, changing "Open With" option of exe files causes a fatal damages on xp that cannot be recovered. Since, the tools and all other programs are exe files and running them becomes almost impossible for an average experienced user.

Changing "Open With" Option of EXE Files

Open "My Computer" / "Local Disc" (where Windows is installed. e.g. C:) / "Windows"; then, right click on regedit.exe, select "Run As" and uncheck the box of "Protect my computer and data from unauthorized program activity" on the menu, then press OK.

Go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe; then delete all key-value pairs at .exe, OpenWithList and OpenWithProgids.