Can Anyone Find Solution for rehabilitating my system?

My PC getting some issues in recent days. As usual i start my work and its going good in meantime it'll be automatically restarted during I'm working on it. i don't know why... If you guys know, then please lead me to recover that problem. I'll be so thankful... Note: I run disk cleanup and fragmenter utility weekly twice and sometimes thrice. Everyday i delete temp files before start... Is there anything i missed to do?

 

Can you provide more details, does it just restart randomly out of no where? That does not sound normal.

 

Of course it restarted haphazardly and there is no beep sound at the time of restarting. I thought that the cause is opening too much tabs in a single window but its cleared that was not the precised reason. Still i confused... Help me please

 

have you to check the event viewer ?
sometime restarted occurs when a hardware or service is fail to load.

 

Sorry i don't know bit of information about event viewer. What is that? And where is this utility? Or is it software?...Ultimately how do i run that? Please give me the answers......