I had a dc yesterday because of menorrhagia, to stop the bleeding, my gyn told me im going to be bleeding for 3-4 days, the dc cure my menorrhagia?

Not always: D&C's are more helpful slowing down or temporarily stopping hemorrhage, but the specimen collected by your doc should help give him/her a possible cause of the bleeding. In general though I do very few D&C's just for bleeding in your age group any more and much of the GYN medical literature says the same thing. Hormonal management is usually the mainstay or surgeries like ablations