ACER 6920G COMPLETELY BLANK SCREEN BUT LIGHTS COME ON + HDD

Hi, please can anybody help me, i'm a week away from my university final hand in and my 6920g has died, or rather the screen has. It is completely dead when switched on, all lights come on, cinedash consol lights up etc, hard drive is firing and spinning up exactly like it would do, but the screen seems to have no signal or power. I have plugged an external monitor into the PC and that is completely blank too as if there is a signal, but its nothing (when unplugged from the laptop, the monitor then says check connection cable so its a working monitor) so far i have been told it may be the ram, the bios, or the gpu, can anybody help. its a well looked after PC and have made no recent changes at all, just switched off last night, then this happened this morning. please please please help, i'm close to tears at the thought of losing my laptop. thanks in advance