You can also first try steam flush cmd ( google it.) might be tried first.



You can find several old steam post with how to reset steam.

Make backup first, ( You can lose steam icon and other own userdata.)

Then keep steam.exe and steam common game Folder.

Dont forget wipe steam user data folder under windows user profile.


ps
Make sure its not Antivirus app that now need steam.exe as exception, i doub't it this unless you change security or its has update its files. ( ppl forget this updateing signature file and core files can change security , for the most time it's never this. ) but you need to get work yesterdau now it don't.


ps.
it's also odd what has change from yesterday to now. most say i did not install or change anything, also why i and other stop ask how is this even possble.


Make backup ppl have lost icon screenshort, and other selfmade things like collection and other though time with steam, and yes they have also change how they work now, poit is i have seen a game devs sue steam own in steam userdta save game loction.

You simple do not wipe steam user data anymore, so yuo can restore past data if you dont know better per game.