I had a tooth absess .resolved after taking antibiotics .2 years no prob till now.today pain coming.doc told me to do root canal.should i do it.

Only if you want to: Keep it. The antibiotics (that helped previously) may not be as effective the next time. And more often than not, when the pain comes back- it will be much worse and more intense.

Most Likely yes: If your dentist advised you, that you need root canal treatment, he/she likely made the recommendation based on some factors, which would have included the tooth's presentation on the xray radiograph, symptoms, clinical presentation of the tooth, and the history of the tooth. If you prefer, you can get a consultation from an endodontist (a root canal specialist) to confirm the diagnosis.

Options: I would have your dentist discuss your options, pros and cons of each, along with long term prognosis. When you understand all this, and if you have confidence in your dentist, go with his\her recommendations. If not or you are just unsure of what to do, you can seek a second opinion from a highly respected and recommended dentist. It is often, but not always best to save teeth.