Laptop either goes into black screen or gets dead

[robs]

My laptop doesn’t start

1. Either it shows a message i.e. ‘NTLDR file missing’ and then shows a blank screen. I can’t see anything even though power supply is on.

Or

2. It doesn’t start at all. I click power button. It tries to start but then goes dead with no power on.

These two things keep happening simultaneously

I recently downloaded defragmentation software and used them. Are they causing it? Or is there any other problem? My friend told I need to reinstall windows, but the problem if nothing appears on the screen or it goes dead, how can I do it
Please help me...

[Orlando]

You haven't mentioned the operating system. Anyways, there are many "NTLDR file missing" related queries available on this forums. You hsould checkout those here. . There is also an Microsoft Article that will help you if you are using Windows XP.