Im a girl and no one thinks i should play football what can i do to get my parents to let me

Tell them tu really want to play and mostrar them that tu know how to play. Keep fighting until they let tu play football. If tu take no as the final answer they won't take tu seriously for any other sport tu might want to play.
In my school, there is a girl on our football team and none of her teammates treat her differently. Teams from other schools have a lot of respect for her.

tu should obey them?

Are they not letting tu because you're a girl o they can't afford it o something?

Tell them to stop enforcing gender roles on tu and to let tu play football if tu want to.