Went 2 dentist. had to leave during procedure and have 2 reschedule & use laughing gas cuz i panic much. ate after and get cold, sharp tender pain in area that he was working on. any reason why?

Hole in your tooth?: Sounds like there is an area in the tooth that is now exposed that wasn't before. You might need a temporary filling or the temporary you have patched up.

Possible if: Tooth was drilled into and then not filled as the procedure was not completed i assume. Try to relax - i know it's easier said than done. See if your dentist can prescribe some anxiolytics to help as well. Will need to have someone escort you. If no help then consider sedation dentistry. Good this helps.

Work in progress: You left the operating room (dentist's operatory) in the middle of a surgical pocedure. Go back and have work completed asap.

Hard to say: What procedure was not completed, or was it completed, but you left? Difficult to determine from your post. Many dentist procedures can result in post op sensitivity, and an unfinished procedure is that, unfinished. You need to work things out with your dentist so that s/he can work and finish what they start.

Nerve exposed: Most likely he had already removed enough of the enamel at least to make you feel the underlying dentin's sensitivity to heat, cold, and pressure, or he had already gotten down to an exposed nerve. You might wish to panic at a more opportune time. Just kidding. Ask your family doctor or psychiatrist about premedicating yourself prior to the next procedure and make sure you have someone drive you.

Can happen: Depending on what work where you getting done..If was a cavity and drilling was started..And if was close to dentin can feel sensitive..Should see your dentist and sometimes putting a temporary fill to cover the area would help block sensitivity.Also that is painless and no drilling involved so can get without being panic..However there could be many other reasons, so should check with your dentist.

It depends: It depends on what he did i am assuming he placed a temporary filling cold sensitivity usually happen if filling is big watch for few days if sensitivity does not go away go back to your dentist a root canal might be needed of course need further test.

Sharp pain: Deep cavities irritate the nerve of the tooth. "working" on that tooth further irritates the nerve short term. If the sharp pain continues the nerve of that tooth has undergone an irreversible pulpitis and a root canal is indicated to remove the nerve of that tooth.