(Redirected) My Leptop keep restarting

Hi guys,

I am facing a strange issue.

I have Dell Vostro Laptop. Today morning when I restarted it, it says "Windows is updating" and progress started from 0-20%. but it stuck at 20% and for many hours, it didn't go beyond 20%. I couldn't wait for anymore so I Hard restarted the system by pressing Power button for 5-7 seconds. 

But after that, the systsm goes until the windows logo appears and then turn to the updating progress(which shows as 30%), disappears and then again restarts from the beginning. And it keep going like this. I waited for another 2 hours but I have observed that it would never come out of it.

Now, I am unable to start the system in safe mode as F8 button is not working(not on my leptop  but by pressing F8 to go to the menu from where we can start the system in safe mode is not working.) 

Can't even do system restore as can't open command prompt as well.

I have searched on various sites/forums but didn't get any concrete solution for my problem.

Any help/suggestion would be appraciated.

Regards

Umesh