Hi i want to ask dat i had a root canal of my tooth two months bck n i fixed a crown on dat toth too,now from lst 2 days m feelin senst to hot n cool?

Highly unlikely: It's highly unlikely (though slight posibility) for a tooth to remain sensitive to cold or hot after a root canal therapy. It's likely another adjacent tooth. If you haven't already told your dentist that you are having temperature sensitivity, call and schedule an appointment for evaluation and x-rays.

Another tooth: After a successful root canal treatment your tooth should not feel sensations to cold, in this case you may have a cavity or receding gums on an adjacent tooth. If the pain is only to hot on the same tooth you dentist need to check the root canal. In any case go back and consult with your dentist.