Wallpaper lock after mac restarting
Apple has a whole article what to do when a restart doesn’t work. Which of these steps fails you?


https://support.apple.com/en-us/HT201262


Once you start in safe mode, you’ll know if you need to reinstall or just make Some changes to the apps you start when the graphical boot portion is running. 

Another tool would be to make a new user to test:


https://support.apple.com/en-us/HT204443


You need a functioning admin account to follow Apple’s steps above and I’ll assume you can’t log in as another user. Here’s a “trick” or procedure to make a new admin account. 


I don&#39;t have administrator account on my mac