Not sure what your Windows version is, but try this:
1 - Press Ctrl + Shift + Esc to load Task Manager.
2 - Press the "File" tab.
3 - Press "Run new task"
4 - Type, without quotes, " explorer.exe ", and then press the "OK" button.
If this does not resolve your issue, save all your work, boot into the advanced startup/boot options menu, backup your data, and try to refresh or reset your system, whichever is more suitable for your current situation. See this article for more information:
https/www.lifewire.com/advanced-startup-options-2625805 - be careful with options you are not familiar with.
If you are unable to access the advanced startup/boot options menu normally, try doing this:
1 - Press Ctrl + Shift + Esc to load Task Manager.
2 - Press the "File" tab.
3 - Press "Run new task"
4 - Type, without quotes, " cmd ", and then press the "OK" button.
3- In the command prompt window, type, without quotes, " shutdown /r /o /f /t 00 ", and then press the enter key, in order to boot to the menu. Save all your work first.