transmission on scag walk behind won't engage in gear

hi. got this scag 36 with Tecumseh tranny. I finished cutting an overgrown lawn today, then the plug under the electric clutch fell out, as well as the transmission just started making an awful sound, like there were gears grinding. none of the gears work, so I'm stuck using the push mower, and all dealers are closed till Tuesday. anyone know what's going on? do I need a new tranny? appreciate any help.