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[unmerged(29957)]

One month ago, I got a virus on my computer. I restored the computer one month, and it disappeared. Two other things also disappeared; the ability to play HoI2 and Victoria. When I try to start the games, a box appeares that says "error: excel file not found" or something like that. I had the MDS installed on both games (the Vic MDS and the HoI MDS).

 

[Castellon]

You may have removed the registry entry fo rthe games.
I have no idea about MDS as it is a user made mod and not supported by Paradox.
I would suggest completley removing the game following the manula uninstall instructions you can find in the sticky thread on the subject.
Then a fresh install and latest patch, see if you can get that working then add user mods as you like.