Missing period for 4 months, not pregnant. polyp removed from uterus 1 yr ago. should i be concerned about return of polyp?

Not at all: Polyp would not cause you to miss your period. On the other hand, it would be more likely to cause you bleeding, so i would not worry about its return.

Well, you are - so,: Contact the doctor who treated you and ask for evaluation and opinion. While you are a little young, menopause might be the reason for not having a period. Your obgyn should be able to help you determine this as well. Best wishes for reassuring answers.