what's the film called with that teenager called matt who changes character after meeting his mom?

there`s a film i watched long ago when i was younger so i don't
remember much but i was curious to know what it was called. All i
remember is that it`s about this teenager called matt and he`s like a
normal teenager acting cool and he sees this woman in a shop who`s his
mother and after that he begins to change to a better guy or
something.