A few things make be causing this issue: - You may be in the wrong mode. - You may be too close to an object. - Try Setting camera to automatic. - Make sure that the background objects contrast well enough for your camera to pick up on.

The lens shutter is probably jammed. be sure to clear out any debris that may be obstructing its ability to open.

The issue lies in your memory space. You can either replace a new memory card, or delete photos and videos. keep in mind a video takes much more space than a picture.

Check the menu, under settings you can change the default mode. You can also manually scroll through your modes each time you take a picture or video.