White Screen Yosemite

Hello I have a early model 2011 mac book pro 15 ", I installed the beta version of Yosemite with no issues, worked for a couple of months then i rebooted, and it would display the loading bar then just go to a white screen, I have bootcamp windows 7 and it works with no issues, I have tried most things i have found online, reset nvram, I cannot access the recovery menu (cmd + r ) it just brings up the loading bar then goes to white screen, i can access the boot menu which is how i use windows, i have tried installing mavericks, and Yosemite both from bootable usb devices, both give me same results loading bar then white screen, just wondering if anybody else had suggestions

thanks