Why computer restart automatically ? When I try shut down PC after select shutdown PC restart. Pl tel what to do?

How old is the computer? What operating system are you using? How long has this been going on? There are so many possibilities as to what could be going on based on your question.

You could have adware/spyware/malware that will reboot your PC automatically. If this is the problem downloading and using ad-aware and/or spybot may fix the problem.

Some autodialers for internet connections will do this also.

If this has been going on for a long time, your PC may not be able to use the Fast Shut Down Feature. There are ways to disable this depending on your operating system.

A little more information is really needed in order to try to help you with this problem.

Marburg