New PC Screen comes on but Black screen

[newmoney148]

I bought a replacement screen for a Lenovo Y510P and installed it the screen comes on but it's black and won't show anything. The PC havent came on for about a year so I thought the PC may be broke but I pluged it into the TV screen and it works just fine any thought on why the new PC comes on with the PC but does not show anything?

 

[webworkings]

So it will show on an external display but not the one you attached. Did you replace it with the exact same display that it had? Also, did you buy that display new or used? And also, did you change the cable that connects it as well?