Hello! I have already researched a bit on this topic, but I thought I'd come here and try to get a second opinion before I send my camera off to its doom, aka the shop. 
I have an EOS Rebel T3 that is a couple years old. It's been used fairly heavily, but never dropped or banged hard that I can remember.
Recently I was messing around with the autofocus points (the little red dots in the viewfinder), and when I tried to set it back to automatic instead of manual focus choice, the AF wasn't working. It would twitch the outer lens ring once or twice, then give up. This persisted over a period of almost a week, during which I reverted to manual focus and ended up with a multitude of blurry pictures. Periodically, it will flash the focus point as if the picture is focused, but it isn't. Now, the ring won't even move when I try to autofocus.
I have cleaned the lens contacts, experimented with different modes, and reset everything to default. The problem is the same with both of my lenses, so I believe the camera itself is at fault. One friend suggested that sand/dust might be interfering, but there is no grating or grinding when I remove/replace lenses and, though I just returned from camping in a fairly dusty/sandy area, the problem began before I left.
Does anyone have any idea what might be wrong, or know something else I could try? There are very few camera shops in my area, short of Sears, and I've never done anything like this before. 
TIA!
