Restoring a deleted registery file?

[P0tat0Phun]

I was trying to delete a virus on my computer, so I had to go to the registry key to delete it. In the process, I accidentally deleted the HKEY_CLASSES_ROOT/.exe/shell/open/comman… file, so now none of my programs won't open. I can't even open registry, system restore anymore, or even task manager anymore! I tried fixing it by rebooting my computer on "Last known good configuration" but it didn't work. Can someone tell me how to fix this? None of my programs or system commands can open properly anymore!