LAPTOP GREEN LIGHT ON BUT NOT POWERING UP

[SIMBARIO]

Hi, first of all I am new to the community and not particularly computer savvy - so please bear with me.

I recently posted an ad about my laptop VGN-FZ21M screen going berserk when connected to the internet.  Well, that was not correct so no wonder no-one replied - it did seem an odd problem.   I actually got it going yesterday and it worked fine. Have only 2gb ram and used 1gb (planning to upgrade ram this week!)  it was a bit slow so tried degrafmenting as advised this might help speed up my laptop but keep all data intact.   This was taking several hours!  Use of internet fine by the way.  Went back into check computer performance and update results (base score 4.9) and the screen went crazy again so had to switch off (it was still defragmenting at the time).  Tried going back in safe mode and it still went crazy. Also it gets HOT  fairly quickly but do have cooler fans underneath.  (I did make the mistake a while back of having it on the bed and feel asleep - it got VERY hot.  Did I do some damage??). 

Status now: green power light comes on but not powering up. Sometimes think I hear a noise thinking its trying but screen stays black and it doesn't power up.  Tried various things with removal of battery etc but still no joy.   Might have some ideas of what might be the problem having looked at various posts but have no idea as to how to solve it.   Whatever the problem is - I am praying that everything on my hard disk is still there??

So HELP PLEASE as to what the problem might be?  Possible solution to try?  Is hard disk data ok?

Thank you.

[SIMBARIO]

I'm responding to my own post because 1) I forgot to mention my viao laptop runs Windows Vista and 2) didn't mean to say used 1gb of memory (said not computer savvy) - HD is 200 gb and have nearly used 88 gb (nearly half remaining).  So did wonder if that was making the laptop slow. 

Anyway, the rest is as per my original post.

Please, if anyone out there has any information on this kind of problem that might get it going.  My own research tells me it could be 

a) the fan (as left hand side of the laptop did get hot despite cooling fan underneath)

b) possibly memory modules

c) graphics card

d) motherboard

Guess logic dictates it might be on the above ?  but if anybody has had a similar experience please advise what action they took. 

Pretty sure the AC adaptor and the battery are ok but still welcome any advice on those.

Thank you very much.