I'm late for my period and im getting worried. Not pregnant. What can bring it on?

Why late? The question i would ask is, "why are you late?" there are medications (progesterone) designed to "jump start" your period if this is the appropriate next step. Occasionally missing a period may be ok while repeatedly skipping a cycle may indicate a problem.There are many reasons to miss a period besides pregnancy (thyroid disease, pcos, pituitary problems, etc.). If this is frequent see a gyn.