Installed GTA 5 Steam version greyed out, Discovering Existing Files, then completely redownloads game?

Yesterday I was playing GTA5 Steam Version just fine, today the "Grand Theft Auto V" font-color in my Steam Library isn't white anymore just greyed out, also the Installation button returned, all fine and good I thought, I had this Problem before, Steam would just find the existing files and I'm good to go but after the loading bar reaches the end it displays "Steam is now downloading GTA 5" which pretty much sucks, I mean it's 60GB come on...

Anybody else had this problem with another game perhaps?

Solution 1:

Worked for me since i was moving a couple of files around in my folder

Open steam and go to steam/settings/downloads

click on steam library folders

make sure the folder your games are in is selected properly