Display not working

Hello,

I have an dell studio 1558, i7 generation. 

Today after some online browsing and a bit of gaming the machine started to be slower and stop the things i was doing for several seconds to tell me that the display driver has stopped and recovered. I kinda torture my computer since it was not restarted and i worked in Maya and Photoshop so naturally i decided that a restart would refresh it. That did not help but instead i noticed some white squares around the dell logo at the start of the machine. Moreover while gaming there was some weird multicolored lines around the display and i alt + tabbed the game so i can close it.

After that the display became on diagonal lines which were white,grey, darker grey and again white, a few minutes later the system restarted itself and the display was just black. I heard the fan working but i didnt even see the dell logo.

I tried several things.

D + power button and it showed that the display is working.

I cleaned the whole system including the fan and every plastic part possible from fine dust.

I connected the system to an external monitor via HDMI cable and VGA.

When connected to external monitor it showed the standard windows 7 screen that the windows did not shut down properly and do i want to go to safe mode. Therefore i let it to start normally and here is a picture of the mistake i received.

Please let me know if i can do something for my system.