When you turn the camera on it gives you an error message "lens error, restart camera" what's wrong?

If the lens is stuck out then you will find it is usually one of a few reasons.

1. Check the batteries. (obvious I know).
2. The camera has been dropped or knocked.
3. The camera has grit or dirt in the lens mechanism.

Providing the batteries are ok then 2 and 3 usually mean a professional repair. The lenses tend not to be something that the average home user can remove and take apart. Sometimes worth giving the camera a slap in your hand or maybe using an air duster to blow down the side of the lens to dislodge anything that might be stopping the lens. The cost of repair also might be more than the camera value so you will need to find a good repair shop near you and get a quote.

If this helps please rate my solution. Thanks