Not working

Check to see if the DC POWER Jack is loose. HOLD the bottom of the jack slightly tilted upward (do not use a lot of force). While holding PRESS the on button.

If it comes on and stays on, you problem is the notorius power jack cold solder issue. The jack will have to be repaired. Either by DELL or a qualified expert that has done a number of these.

It is not a easy task by any means. A skilled ELECTRONICS TECHNICAN could do it. But not a Computer Technician, because they generally just replace parts and do not do component level repairs

It could be a variety of things, did you hear the other parts spinning and whirring as before? Then it could be just the screen or video card. Try hooking it up to a regular monitor and see if it will display there. Other problems could be HD failure, but usually your computer would freeze on startup or your BIOS will tell you that instead of a blank screen. Have you tried contacting the manufacturer for tech support on the issue? It is hard to diagnose blank screens over the net due to the lack of information you can get (ie. error messgaes, etc.....)

The monitor might be off, because it's possible on most Laptops that you can turn the monitor on and off.

If you're getting ANYTHING readable on the screen, the problem is likely not the screen. Dim screens are one thing, and messed-up screens are likely problems with the physical screen. If nothing's showing, it's likely the connection running through the hinge into the screen, which can be a little tricky on laptops, though the whole connection between motherboard and screen is suspect. This is a problem because the problem isn't always immediately visible even upon opening the laptop. You might do so, if you know what you're doing, in order to examine and reconnect everything. But you're likely going to have to pay to have the wiring repaired (and maybe even the screen itself, though that's far less likely).

my problem about all display. no start and can use keyboard too. and when i try to look in folder there is change everytime.. Please HELP...

I am afraid it is not a solution only to repeat the problem I have exaclty the same. It appears to switch on but then nothing not even mumlock light or caps lock light comes on or off

I had the same problem with my C640. What I did was take out the memory chips powered up. Then turn it off and reinstalled the chip, and poof. Every was working. I hope this will save your problem to.