How to revive a computer if it functions in an unexpected manner?

This would depend on the issue the computer is having. 

In many cases though a simple reboot does the trick. 

If your computer is slow and glitches, try cleaning it for viruses and also clean the fans. If they are dusty the computer can overheat and that can cause it to slow while its working harder to cool down.

In other cases you may not be running the proper software compatible with your device, or programs may be outdated. Check online with the company that manufactured your computer to see if you need to install updates or change certain software.