Your power supply unit is the part of the computer that typically attaches via cord and connects it to your wall. It then provides your computer with the electricity it needs! If your computer is turning off randomly, or not turning on at all, it could very well be a problem with the PSU. Maybe you need to upgrade the part, but that’s not likely, we should just need to take a good look at it.
How do I know if I need to repair or replace my PSU?