Replaced broken screen, but its just black!

Hello,


I dropped my HP Pavilion dv7 and hooked it up to an external monitor, and picture showed. I replaced LCD screen and it worked great for 2 days. Now all of a sudden it just lights up black. All icons light up and I hear the startup sound of WIndows. I hook it up to my TV and the picture is there. What could be the problem? I tried rebooting and unplugging for 30 sec. I appreciate any help or recommendations regarding this issue. Thank you.