I didn't have a period for 9 months and was not sexually active. my doctor said i was probably starting menopause. i recently started becoming sexually active again and all of a sudden had a period again. can sex cause this to happen?

At age "47", ovulation occurs much less frequently, so the period which occurred may just have been withdrawal bleeding from sustained high estrogen levels w/o ovulation. Sex does not contribute to the onset of bleeding, although irritation of the cervix can cause bleeding from an inflammed cervix. See your gyn provider for an exam and other testing..