Dell Inspiron 1525 screen goes black

Hi, I've got a Dell Inspiron 1525 and my screen went black when I turned it on and if you really try, you can see a very faint image on the screen. I hooked the laptop up with an external monitor and got a perfect image of the screen so suspected that it might the inverter that gone busted. Ordered a new inverter and just replaced the old for the new...and the screen is still black :(. I was wondering if anyone has any ideas/suggestions/advice to my problem at all? Many thanks in advance for your help. Chloe