Screen keeps going black Help!

Hi I am using a 13" mid 2009 MacBook Pro with Lion.

The screen on my computer went black today and couldn't get it to recover. I switched it off and on by holding down the power button for few seconds. It starts up nicely screen comes on. The animated loading icon comes up on a white screen. Then it gets to the user login stage (still on as usual) I click on my user icon then bam! An all black abyss of frustration that's threatening my bank account!

So on and off again, same story, then gets to user login stage then this time the screen goes black after just couple of seconds.

The keyboard backlight won't come on.The sound does still work, I it up my Mac tells its already on full with the "blep, belp, blep" SFX.

Whats wrong with my Mac? I fear its a hardware problem and may be the motherboard. I am not sure I am using the correct power supply, I may have been using one of my old magsafe of chargers for a 15" but the one I am using now does seem to work find and is fully functional with this computer correct or incorrect.

All help much appreciated ...and needed right now too 🙂