Computer not recognising Camera...

I have a sony cyber-shot camera. Usually when I plug the USB cord of my camera with the computer, it auto runs and is recognized by my computer.
For some reason, my computer has stopped detecting my digital camera.
Why?What should I do?

Connect Digital camera connect to an IEEE 1394 card

To get the best quality from your digital video (DV) camera or mini–DV camera, you should have an IEEE 1394 capture card installed on your computer.
An IEEE 1394 card is a piece of hardware that passes the information from the DV camera to your computer. Because the data is already in digital form, it can be read and transferred directly to your computer without any processing or conversion.

thanks...but i don't have IEEE 1394 card

If you use a DV camera, but don't have an IEEE 1394 card installed on your computer, you can still capture video recorded with your DV camera as long as you have another video capture card installed on your computer. Because the data that is passed to the capture card must be processed before the computer can use it, when you transfer video from a digital device to an analog capture card, there will be some loss in quality.

When you connect a DV device to your PC using an analog capture card, there are two main types of input: S–video or composite video. If you have the appropriate connectors and your hardware can use either S–video or composite video, you'll probably want to use S–video because it delivers higher–quality picture and sound.

Change the USB settings in your camera.Sony digicams have three settings for the transfer modes. Once you will change the settings in all the transfer modes, then camera will be detected.