I've seen a few threads like this open up today. I am also running into the same issue. Reinstalled, moved drives, etc. Shows up in the Task Manager, no client opens up and you can't open games manually. I put in a support ticket to Steam. Maybe if enough of us put in ticket it'll get their attention.

Here's another discussion on it:
https://psteamcommunity.yuanyoumao.com/discussions/forum/30/682986292645128399/