Digital camera pictures only showing on the camera but not in computer

My sony digital camera has been working fine for a year now. It has a memory card inside it. Recently, when I decided to transfer the pictures to my computer, we can only see 5 pictures instead of the 1000 that I actually have. When I plugged the memory back to the camera and go to play the pictures, it’s all there showing 1000 pictures. Why is it not showing on the computer? What should I do to transfer them? How can I save my pictures and not ending in deleting all of them.
