Broadly speaking, there are two possibilites.

1. It's caused by a software problem. Although sometimes that can be solved inside Windows, it's quite common to not spend time on that and just reinstall Windows from the recovery disks that came with the PC or that you made.
2. It's caused by a hardware problem. In that case it's necessary to visit a repair shop to have your PC repaired.

Based on the information you give, it's not possible to tell what to do best. So better go to a repair shop and let them fix it. They not only fix hardware problems, they can fix software problems also.

Kees