Q: My camera keeps shutting down when I try to take a picture

I've used my camera successfully for several months.  However, last weekend it began having problems.  I would focus the lens, hit the button and the camera went black.  I had to try several times to get a picture.  Now I can take a picture of me while holding it, but I cannot take a  picture of something else.  I get a black screen and then see the subject.  Once I push the button to take the picture, the screen goes black again.  Please help.