If the mouse cursor is not moving at all, and the screen brightness / dimming and sound up / down buttons are not working on the keyboard, then the Mac is probably frozen and must be force rebooted. If the Mac is stuck on Screen Saver and totally unresponsive (mouse cursor does not move, keyboard doesn’t respond)

You can also try Control+Shift+Eject if you have an Apple keyboard with the eject key, or Control+Shift+Power if you have a Mac keyboard with Touch ID or no eject button. Since there is no lid to close to sleep the Mac, the solution in this case is a reboot of the Mac, which we’ll discuss next. On Mac desktops like iMac, Mac mini, and Mac Pro, you can try the Lock Screen keyboard shortcut (Control + Command + Q) or the Log Out Shortcut (Command + Shift + Q), but both of those don’t always work and you may have to turn the Mac off and back on again. This should prompt the regular login or wake process, and the Mac will be usable again. Wait about a minute, then open the lid of the Mac laptop again to wake the Mac from sleep.

On a Mac laptop you can put the Mac to sleep easily by simply closing the lid of the MacBook Pro, MacBook Air, or MacBook. If the Screen Saver is stuck but it’s still moving and active, and you can continue to move the Mac cursor and the keyboard responds to volume up/down and brightness adjustments, then you can usually fix the problem by putting the Mac to sleep, or trying to initiate the lock screen. If the Screen Saver is stuck but active on the Mac (and you can move the mouse) In either case, the troubleshooting steps below should help to fix the stuck screensaver problem on a Mac. Sometimes the screen saver can get stuck but it’s not active or moving at all too. The most obvious symptom of this problem is just as it sounds the screen saver is enabled and active, but the Mac won’t respond to anything and you can’t get the Mac to prompt the screen saver unlock or wake.

Reddit picture screen saver mac