I've tried a repair and stem replacement for a 3 handle tub/shower set. The diverter once installed will not turn to allow water to flow either from the tub spout or shower head. The hot and cold handles turn fine, but no water pours I assume because the diverter is some how blocking water flow. And yes I turned the water back on.

Shut water off and remove diverter. Turn water on to see if you have a flow.

If not then you have problem with shut off valves or blockage in tub/shower body.

If you have water, then it is possible you have the wrong diverter valve.

Chuck

but no water pours
Does that mean NO water or no water from tub spout?

Loosen bonnet nut around diverter stem, turn diverter to tub position, which is probably all the way counter clock wise. Tighten bonnet nut.