Do You Know the Milkyway? (1985)

Kris, thought lost in the war, returns home to discover that the town has decreed him dead and taken all of his land, home and goods. He sets off to find a means of survival and ends up in a series of catastrophic encounters with assorted villains which gets him committed to an insane asylum, where he tries to convince doctors that he is perfectly sane and actually comes from another star.