Does uterine ablation stop working after many years or should i seek help for drastic change in menstrual flow?

This is not normal: If you are getting your menses again years after an endometrial ablation, this is considered a failure. It is important to understand that 15% of ablations fail, higher if you have fibroids. You do need a gynecological evaluation to make sure all is ok. There is no indication to repeat an ablation, not even another type. You may want to consider a laparoscopic supra cervical hysterectomy.