Start off with the simple things, does it work with another lens, is the AF/M switch in the correct postion for autofocus (AF), are the batteries good.

If all of the above are in order it maybe either the DC/DC converter on the bottom of the camera, this supplies power to various parts of the circuit. or it could be the motor drive transistors, these are located under the front cover and are located where you finger tips rest on the right hand side as you hold the camera.

Both these items are not really user changeable and I know the DC/DC units have not been available new for many years now.

I suggest you have a look for a friendly camera repair shop to pin point the exact cause.

You will have to keep in mind the age of the camera 23 years old parts are a big issue