Why does my macbook pro keep restarting itself

Restart - computer spontaneously restarts

Pretty much impossible to answer without more information?

Does it generate a kernel panic log? Look in /Library/Logs/DiagnosticReports/ for a file whose name starts with kernel. No other report in that folder is useful. It must be one whose name starts with Kernel.

If you find one, open it and copy the text. Paste the text into the Additional Text section of a reply, here. The Additional text button is the one that looks like a document icon.