Sony Vaio PC unresponsive black screen

Hi all,
I have a Sony Vaio PCG-2P1M PC which upon startup only comes up with a black screen, the only sign of life being the green power LED at the top and the PCs fans. The entire system is unresponsive to the methods I have tried (which isn’t very many as I can’t find anything in this model anywhere).
The PC has recently had a fix (about a month or so ago) due to a similar problem, the only difference being it wouldn’t let me log in. Could the black screen be related to this problem?
The PC currently runs on Windows 7
Any help as to how to get my PC back up and running would be greatly appreciated!!
Thankyou!