No logo or start up screen,just black

Recently i updated my M17x R2 laptop,windows 7, ati 4870x2 graphics, 2 x 320GB hard drives,and all of a sudden little blue screen came up, all i had time to read was something about video drivers update,then computer shut down,now when i start up all i get is black screen,nothing else not even logo screen,i am certain this is not hardware problem as everything has been running perfectly,its something to do with the updates,unfotunately cd/dvd drive is broken so my only option is to do something through USB,only problem with that is i cant get into bios F2 or boot menu F12 to change boot order because screen black,so i need something on USB that will overide the bios/boot,also tried pressing F8 and nothing,but when i do start up everything sounds fine,fans,cpu,its just screen,could you please advise,any help much appreciated