04 chevy aveo, stripped timming belt, after down shifting, engine died quietly without sound, suggestions???

my aveo engine was hot from traveling on hot highway in mid summer, in hot summer sunshine, and I had to down shift to slow down because of slower speed limit, as I was traveling at 120 km per hour, dropping to 80 then 50.traleling at 120 km and dropping gears 5th to 3rd as I slowed down applying brake pressure, all of a sudden, without a sound, my aveo engine just quit after downshifting, realizing this I applied clutch right after, so I could turn ignition key, with no result. so I pulled over and stopped. trying again, starter engaged then dis engaged quickly, with out starting.