So I recently came back from a vacation. My PC was untouched for about 20 days. When I came back home I cleaned and booted it but ran into some serious issues. Whenever I try installing anything I get an error saying that the setup has failed because the files are corrupt. I have tried installing games such as sunless sea, stalker (which are both bought from GOG) and Fortnite. They have all failed. I ran Windows memory diagnostic tool and it came up clean. I have windows 7 64-bit. What do I do?