As you can see, the default shortcuts are 'Shift-Command-3' for entire screen capture and 'Shift-Command-4' for partial screen capture. Click the 'Shortcuts' tab then select 'Screen Shots' to check if all the shortcuts have set properly. Go to the Apple menu at the top of your screen, select 'System Preferences' then 'Keyboard' to enter Keyboard setting. Follow the steps below to check if your shortcuts have been set properly. In this case, you may need to check your keyboard shortcuts settings. If you have restarted your MacBook but still fail to take a screenshot properly, it's possible that the shortcuts for screenshot have conflicted with other shortcuts. If you hear the shutter sound then go to Desktop folder to find your screenshots. Once your MacBook has been restarted, try to take a screenshot again by using the shortcuts that you previously have set and see if they work. Hold down your power button and select 'Restart'. Go to Apple menu at the top left corner of your screen and click 'Restart',
To fix screenshot not working problem on Mac, you can try to restart your Mac. Change to TuneFab Screen Capture to Take a Screenshot
