After years of wonderful and trouble free picture taking, somehow, my camera now
only takes 4 pictures and then says INTERNAL memory is full. I can't find anything about INTERNAL MEMORY in my instruction booklet - don't know how I got it on there and now don't know how to get it off so I can once again use the camera.
Internal memory is the storage built into the camera itself. All cameras come with some amount of internal storage, otherwise you would not be able to take pictures right out of the box, but typically it is quite limited. That's why most cameras allow you to insert additional flash memory cards/chips into the camera, to greatly expand your storage.
So you don't want to "get it off" your camera. However, you might want to find out what's filling it up, and, more importantly, why the camera has no auxiliary memory storage. Did you never add a flash memory card to your camera? If not, then your camera has simply filled up it's internal storage (memory) with pictures and you need to delete them (you might want to copy them to a computer before deleting them from the camera).