Santa Who? is about ... Santa! He crashes into the roof of a department store in New York and suffers amnesia. Although he can't remember who he is, everyone else seems to think that he's the store's Santa.

Elves are panicking because Santa has gone missing. They do actually find him in the 'Nick' of time and Christmas is saved!

There's a sub-plot, of course, involving getting people together and all that sentimental seasonal stuff.

I think the film was originally made for TV and therefore wasn't shown in cinemas but with Leslie Neilsen involved, it's funny/silly and worthy of some family viewing time.