Authenticatino web cam?



I connected my webcam to the raspberry pi. I accessed it through an external no ip address. It was working then. I tried to get my camera in focus. I refreshed the no ip address a couple of times (it was not giving the images lifetime). Now I get no webstream anymore!
If I try to get my web cam stream it says it may require authentication. How can I do that?????????
If I try to get my webcam images through my network I get the same message.
What is wrong???