Help please my computer has blask screen at startup?

i have windows vista. i had a virus & system restored and after that it didnt display a welcome screen, just a black screen with a cursor. i tried all safe mode options, nothing worked. i tried ctr alt delete and nothing popped up. sticky keys works but it doesnt help. i do not have a boot disc or vista cd, i think it was thrown out. i dont know what to do so please someone help me out. im trying everything i can.