|Accompanying the blue screen there is usually an error message.|
If your system reboots before the message is displayed then you need to turn off the automatic restart in your system settings.
There are many possible causes for a bluescreen and without the error message we have no way of advising what direction you should proceed.
The other possibility is a can of blue spraypaint exploded in front of your PC. If this is your problem then wipe it off before it dries.
Goin' Fishin' (Some day)