Had bluescreen a number of time, but laptop always booted up again. However i now have a black screen and nothing will boot up,even tried the dell recovery disc, but nothing. Any ideas?Thanks

Worth a try:
plug in an external monitor and see if it works. If it does, your screen might have become unplugged (happened to me) or may need to be replaced.

Dell includes a series of tests for a system's hardware into the BIOS called the PSA+ Diagnostics. You can run these tests even if the system lacks any media (hard drive, CD drive, etc.). To launch the PSA+ Diagnostics on this system, perform one of the following actions:

• Hold down the key while pressing the power button.
• Turn on the system, press at the initial Dell™ logo screen, and select Diagnostics from the boot menu.
• Disconnect the AC power and remove the battery. While holding down the power button, insert the AC connector into the back of the system. The system then starts and the message Diagnostic boot selected displays. The system then launches the PSA+ Diagnostics.
• If all tests pass you will need to re-install the operating system software.