XPS 15 screen won't come out of sleep/hibernate mode

Hi, 

I have a late 2011 model XPS 15 that no longer wakes up from sleep or hibernation mode, at least only the screen doesn't.  The computer will start up but the screen stays black, not even the backlight will come on.  I can hear it working but nothing happens.  

I am open to suggestions as at this point in time I am too broke to go out and purchase a new computer.  

Also I should mention that this was all happening over 8 months ago and I have tried a few things, but now my battery is shot so I'm waiting for a new one to come in.  

Thanks, 

Meg