why is steam telling me to install a game again

Please help! It's becoming infuriating having to wait for my games to have to update before I can open every time I open Steam. I've looked around online but have found nothing that relates to the issue, the nearest being that Steam itself updates when opening. Recently I’ve been wanting to play the game but now it’s telling me I have to buy the game again. I've reinstall a game or two, and that solves the issue until another update rolls around, which can't be an option forever with games getting ever larger. GC GameBoy CoIour Created on JanuGame I bought needs to be purchased again A while back in 2018 I bought Hello Neighbor when it was fairly new in the xbox store. I've reinstalled Steam and that have no effect whatsoever.

This initially started when I was running Windows 10, but I have since returned to Windows 7 and the problem remains. Sometimes a game initially says it is updating but then gets stuck validating itself indefinitely. I'm not sure if this related at all, but when I try to uninstall a game through Steam it will say that it is uninstalling but ALL the game files remain, including the appmanifest, and the game reappears in my installed games list following relaunching the program. So far it has to download updates for five games, but this is sure to rise. Every single time Steam is opened, whether just restarting Steam or the entire PC, any game that has received an update since the game was installed will re-download the entire update again.

Why is steam telling me to install a game again