Most likely it is a driver problem if it wont allow you to adjust settings. These are the steps that will alow you to fix the problem. Total estimated time is about 2hrs. Print these instructions out BEFORE you begin.
1. You will need to do a factory reset which will take your computer back to when you first turned it on out the box so save all of your files and anything important such as programs and what not. THESE INSTRUCTIONS ARE FOR HP users. It may vary with other brands but its along the same lines. You can pretend to go through the insturctions to see if you find all the labels Im talking about first.
2. CLick start. In seaarch type "manager". Click on device manager. Then under "sounds, video and game controller" you will find your webcam device driver. Right click and select uninstall
3. Then you want to click start and then type "recovery". Click on "recovery manager" . Then you want to click on system recovery. This process will take some time so be prepared.
4. Then follow your setup steps as if you just got your computer out of the box and your webcam should be working fine now!
Hope this helps. If not then you will need to uninstall youcam and reinstall it but the first steps should fix it!