Watch the video:
Timestamps:
0:00 - Explanation
0:15 - Launch games via Steam
0:59 - Restart PC
1:02 - Manually check for Steam updates
1:23 - Join/Leave Steam Beta
1:50 - Verify game files
2:30 - Run Steam as Admin
If you’re trying to play any Steam game and getting a “Steam must be running” error, this video is for you. It runs through the simplest solutions to this issue. You should be able to get back into your game shortly.