Radeon HD 6670 no display

Hello, I recently purchased Sapphire HD 6670 1gb gddr5 and it worked perfectly on my system for almost a month. Then, a few days ago, when i boot up my computer there was no display on the monitor not even the BIOS logo but I can hear the Windows startup sound. I tried connecting my monitor to the onboard graphics and it's perfectly fine. I uninstalled then reinstalled the driver but still no display. I reinserted my card and still same problem. Please Help! any help is greatly appreciated  

My specs:
AMD Athlon 64 x2 4600+
MSI K9N6PGM2-V
2gb ddr2
100gb HD
Antec VP550