My pc dont have communication with the modem

i tried to reformat my dell pc which is the OS is windows xp because of some viruses, after that when i check the internet it says this page cannot be displayed so i turn off the modem for 10 sec and then turn it on again, i check all the lights of the modem and everything is normal, i check my laptop for wireless connection and i still have it, i only got a problem with the pc that i reformat so i tried to go to device manager and see f i can find the driver of the modem on it but i cant find any, ive seen some yellow question mark in there under network adaptor. so please help me to solve this problem..thank u all so much!