When using Weedeater lawnmower last time, hit a rock. Mower shut down... cannot even pull rope to start. Where should I look for resolving problem?

Remove plug wire and plug and try to turn blade by hand.

If it bangs against something then you probably threw a rod. Internal engine damage.

The flywheel key is supposed to protect against this, so it's probably compromised too. If it were sheared or damaged the pull start would spin with no resistance or engine would backfire and not start.

Make sure the blade is not bent up against the frame, that will foul the rope. Good luck

Thanks for the advice! Acted on both of your suggestions and everything looked okay. Neighbor came over and looked at it. Replacing the blade adapter.