Both webcams stopped working

I have a Sony Vaio VPCEB. It has a built in camera at the top of screen (USB 2.0) and I also have an external webcam (microsoft LifeCam). Both were working fine until a month ago. But now they do not work. Can somebody help me find what can be wrong?

More details:
1. Both cams were working until a month ago
2. Both cams show up in Device manager under Imaging Device with status "This device is working properly."
3. None of my programs are unable to detect either of the cams (skype, google talk, ArcSoft Webcam Companion).

4. I had turned on a few services (because my computer became too slow), so I thought that could be the reason. So I tried turning on ALL the services, but no success.

What else should I check?

Any ideas what else can be wrong?

No I have not used any registry cleaners.

I am so bummed, I still need help.

Here are screenshots in case somebody can see what else can be wrong

Update: issue fixed.

I uninstalled both cams. Restarted the machine and windows automatically reinstalled both devices. Now both cams are working.

Never came to know what was wrong.

P.S.: I got this idea after I fixed a DVD drive on a friend's computer about an hour ago. Looks like the solution works for many hardware devices.