The membrane (hymen) can be broken by riding a bike, inserting anything into the vagina, having sex, or doing a rough activity.
Losing your virginity is the act of having sex with another person. Sometimes a female can have her hymen broken when losing her virginity, but no longer having a hymen doesn't mean you're not a virgin.
Please know, whether your hymen is broken or not, that it is up to YOU (and no one else) to decide if you are or are not a virgin.