Windows 7: laptop will not switch on advent k4000

any advice for me please
i have an advent k4000 laptop and sometimes i just will not start up at all
i switch it on get power on light the hard drive light flickers little bit then just get blank screen.
other faults i get sometimes get power light and caps lock and number lock light comes on but does nothing.
i know when it is going to work properly is when power light comes on then hd then wireless light comes on.
is there any checks i could try to work on the problem
not sure if its hd problem or what.
but when i do manage to get working the laptop it self is fine.
tried allsorts stuff from youtube to sort problem but really not sure what the issue is
any ideas would be greatful
thx in advance

Hiyya pealy try this mate for starters if you can get it running SFC /SCANNOW Command - System File Checker