First try pressing the DISP or DISPLAY button on the back of your camera.
If that didn't help, check if your camera is in this list:
A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S230, S400, S410, S500, SD100, SD110, IXUS V2/V3/300/400/430/500/II/IIs, IXY Digital 200a/300a/320/400/450/500/30/30a
Then see this article
But if your camera is not listed, A stuck shutter is another common failure mode for digital cameras. 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.