"Street of Chance" is an old movie that was meant as a B-movie. In other words, a shorter and cheaper film to accompany the main feature. So, even though the story is filled with some silly cliches, I could look past this because the movie wasn't intended to be perfect...or anything close to it!
Frank (Burgess Meredith) is walking down a city street when debris from a building falls on him. He's mostly okay...mostly. Although he hasn't broken any bones, he has broken his brain. In other words, he has amnesia and can't remember who he is and has trouble remembering recent details of his life. Eventually, he learns that he's wanted for murder....and he's determined to prove his innocence. To help him with this is a woman (Claire Trevor) who tells Frank she's his girlfriend. But can he trust her or anyone else??
The notion of getting bonked on the head and developing an all new personality is popular--particularly in 1950s and 60s TV shows. In reality, such accidents and reactions are rare. Again, I wasn't trying to say it was believable...just mildly interesting and mildly entertaining.