Yes, as long as you haven't had sex, you are still a virgin. Some girls worry that if they use tampons, they will no longer be virgins. The truth is, a virgin is someone who has never had sexual intercourse. Inserting a tampon is definitely not the same as having sex!
So why do people ask this question so often? Girls who are virgins usually have a hymen, a very thin piece of skin-like tissue that partly covers the opening of the vagina. The first time a girl has sex the hymen stretches and may tear and bleed a little. That is why people say the hymen is "broken."
Other things also can cause the hymen to stretch, such as putting in a tampon (although that usually doesn't happen). But even if a tampon does stretch a girl's hymen, she is still a virgin until she has had sexual intercourse.