Annlane123, Since you have been taking photos in one of the other modes, say shutter or aperture mode you may have changed the F-stop in the process, check to see that the ring is set back for auto mode by aligning the red numbers (ususally F-22) to the white dot on the lens, that way when the camera in auto needs more light the lens will open enough to allow it. Test it with the metering in the viewfinder you'll see it as you change to each number. Remember both the lens and camera are communicating with each other. Not allowing the shutter to release is kind of a safety. randy320sgi
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Annlane123,
Since you have been taking photos in one of the other modes, say shutter or aperture mode you may have changed the F-stop in the process, check to see that the ring is set back for auto mode by aligning the red numbers (ususally F-22) to the white dot on the lens, that way when the camera in auto needs more light the lens will open enough to allow it. Test it with the metering in the viewfinder you'll see it as you change to each number. Remember both the lens and camera are communicating with each other. Not allowing the shutter to release is kind of a safety.
randy320sgi