Prime lens on rebel xti works fine. No image and can't shoot with zoom lens?

Question

battery ok, cap off,memory card ok. As newbie i think i pushed /set a button i shouldn't have

Answer 1

Try cleaning the contacts of the lens with a pencil eraser and DONT GET THAT c**p ON YOUR SENSOR!!! You can also do the same on the body but your really run a great risk of dirtying up your sensor. That will leave spots on every single shot you take in the exact same spot.

If you do get your sensor dirty, take it to a pro shop to clean for you. If you damage the sensor it will be cheaper to buy a new camera than to have it fixed.

Make sure the battery door is closed and the memory card door is closed. You should see the memory card light blink when you close those doors.

Answer 2

"Can't shoot"--as in what? It doesn't focus?

Or you don't see anything in the viewfinder. Do you see "error" message at all in the LCD screen?

Did you switch it to M (for manual focus)? Are you able to turn the focus ring to get things in focus? Which lens are you using?