The flash insists on going off even when I don't have it set to do so,

The flash goes off even when I set my flash to stay off. It also acts sluggish carrying out tasks. That's the only way I know how to describe it. I cannot snap photos of objects from various vantage points as quickly as it used to do. I have changed the battery. I know it's not the best camera for photographing objects to sell, but when I got it did a pretty good job. I cannot afford a new one and I'm wondering might something on it need to be cleaned? Thank you.