Why Restarting Your Computer Works So Well
When your computer is running, you open and close some programs, leave others running, and maybe install or uninstall software or apps. Lots of other behind-the-scenes processes stop and start, too.

Many of these actions, as well as your operating system, leave behind a kind of electronic footprint, usually in the form of background processes you don't really need running anymore, or programs that don't quite close all the way.

These "leftovers" hog your system resources, usually your RAM. If this happens too much, you get problems like a sluggish system, programs that won't open, error messages, and other issues.

When you reboot your computer, every single program and process ends as the power leaves your computer during the restart process. Once your computer starts back up, you have a clean slate and, usually, a faster, better working computer.

https://www.lifewire.com/why-does-restarting-seem-to-fix-most-computer-problems-2624569