Canon S2 Is digital camera not able to shoot

You fail to mention the details of your problem. But as you own an S2 IS, I'll assume that your camera is showing a dark LCD screen, and is taking similar black picture (very common problem for the S2).

A stuck shutter is a common failure mode for digital cameras, especially the S2. The symptoms of a stuck or "sticky" shutter are very similar to CCD image sensor failure. The camera may take black pictures (for shutter stuck closed), or the pictures may be very bright and overexposed, especially when taken outdoors (for shutter stuck open).

To confirm a stuck shutter, put the camera in any mode other than "Auto", and turn the flash OFF (you don't want to blind yourself for the next step). Next look down the lens and take a picture. You should see a tiny flicker in the center of the lens as the shutter opens and closes. If no movement is seen, then you likely have a stuck shutter. If so, please see this link for further info and a simple fix that may help.