You want to look at your system event viewer. Your event viewer is in your administrative tools. Then you want to click on the Windows logs tab on the left side of the window. Then click on the system tab. Look for a red error event in the top center window. Read the errors descriptions, and see if any of them say loss power.
i have checked that now and i found this
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly
can this be something ?