If it does nothing and no sound be sure outlet is hot, plug is good or
pump switch is bad. If it makes noise but doesnt run it is frozen either
the impeller or motor. You can free up pumps, a switch may be special
order. New pumps are cheap and can give you a back up. If your in no
flood danger work on it, pull it out to find where it is binding . You
didn`t say you heard anything so it is likely electrical as you would
hear it straining to move, humming. Usualy an easy fix but since it
hasn`t run in a long time you can`t know till you try.