I was playing GTA5 and when it quit, my monitor said it was going into standby mode.
I've been having problems with build 10074.
Anyway, a quick fix which doesn't involve hard-restarting is to follow this process and have faith:
Hold the WINDOWS KEY and push R
Type SHUTDOWN /L
this causes windows to log out of your account and the login screen should appear. You can simply log back in.
Putting your computer in standby might also do it.
Maybe windowskey+L too.