Reason 1: Too bright pictures due to high ISO
Solution 1: Check your ISO settings. Under high ISO value, It's quite usual for the camera to capture too bright pictures, if the camera is set to use flash. Set the ISO of camera to small value while using the flash. The problem would be solved.
Reason 2: Too bright pictures due to brightness control settings
Miscellaneous Reasons and Solutions:
If none of the above solution works, then the camera flash itself is causing problems.
Solution 3: Try to capture images by turning off your camera flash and setting the ISO to it's highest value( quite obviously this trick wont work if you are capturing images in darkness )
Solution 4: If using the camera flash is a necessity, then try to capture images by temporarily placing a small bit of paper on the camera flash. This trick must work