Web cam wont work plz help!!!!

Hello, i have installed 8.0 and i have 8.5 i cam to get my web cam to work it was working then quit .i dont have mcafee so i know it is not that !i use panda and had no problems before but now my cam wont work . it says we cant find audio video .went to tools to try help but the boxed wont appear they are all grey have tryed alot of things plz any one who can help me i do video with my kids that are 1000's of miles from me and now cant see them at all thanks for any help