The hymen is broken by doing sports, falling (I don't recommend doing that on purpose), horseback riding, dance, tampon use, and countless other non-sexual happenings. It can even be broken accidentally during a pelvic exam, and sometimes doctors will intentionally stretch a girl's hymen if it have no first or the passage is drastically small
You check if you hymen has been broken or not by... sitting on the edge and have a shaving mirror with someone holding the mirrow because idealy you need some one to hold the mirror for you, because its a bit awkward to hold your outer vulval lips open , and then open the inner lips to see you hymen.
the hymen is usually crescent moon shaped at the lower part of the vaginal opening.
you will need your legs open very wide to be able to see properly.
you should also be able to see your clitoris, and your uretha as well. although for some ladies the clitoris is not exposed to view, but is hidden by the clitoral hood.