This works with both pop-ups and rotors. Sometimes it is possible to just replace the sprinkler guts.
When the sprinkler is broken but the body is not damaged, you can replace the guts instead of the whole sprinkler.
Expose enough of the sprinkler to have access to the top. Unthread the top retaining ring of the sprinkler that contains the guts and remove them. The replacement guts will have to be from the exact same model of sprinkler for this to work.
Remove the guts from a new sprinkler head.
Simply insert the new guts into the old sprinkler head body and tighten the retaining ring. Insert the proper nozzle to complete the repair.