I had two root canals done on top side by side and took me two years to get back to the dentist (different one) to get the crowns done. I went in and told the (assistant I think) the situation and she took the x-ray and told the Dentist what I needed (I assumed) he did grind two teeth down but only ground down one with root canal and my other tooth closer to the front (Not aware of any root canal) I was numb and could not tell until it wore off. It hurts to tap on the front tooth and I go back Saturday to have the permanent ones put on. I don't know how to approach the subject. Should I ask to see my x-ray? I don't know what a root canal looks like... HELP

Sure ask him to see the x-ray just for curiosity... if it is sensitive to hot/cold then it definitely does not have a root canal on it. On an x-ray, a root canaled tooth will have thick white lines filling the inside of the roots.

Definitely ask to see the x-ray! As Amir said root canals will have a white filling material in the roots of the teeth. You certainly shouldn't be having any sensitivity on a tooth that's had a root canal.