Why sometimes i miss my period and never have sex?

Anovulatory cycles: if you have a cycle and do to ovulate you may not have a period. If concerned check with your physician.

Common problem: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections & hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.

Missed periods: Many things can cause delay of ovulation, including stress caused by job, relationships, depression. If ovulation does not occur, you will "miss" your period for that cycle. Oral bcp may be a solution, even if you are not sexually active, because the bcp's will cause your cycle to be regular in response to the fixed doses of hormones in the bcp.