If I am being sued for a bad debt but the account that they are suing me for is not my account, do I contact the lawyer or just go to court?

You can try contacting the attorney to ask that the attorney file a dismissal of the lawsuit against you.  If a dismissal is filed with prejudice, that means the lawsuit against you cannot be reinstated.  If a dismissal is filed without prejudice, that means it can be reinstated in the future.  You should ask for a dismissal with prejudice.  If the attorney agrees to a dismiss you from the lawsuit in a telephone conversation, you should immediately send the attorney a letter confirming that telephone conversation and keep a copy of the letter for yourself so that you have evidence of the attorney agreeing to the dismissal. 

If the attorney refuses to dismiss you from the lawsuit, you should file an answer to the complaint (complaint is the lawsuit attached to the summons).  You will need to file with the court your answer to the complaint within the time period set forth in the summons.  Attach a proof of service to your answer to the complaint and serve your answer to the complaint on the opposing attorney.  An answer to the complaint denies the allegations in the complaint.  If you don't timely file an answer to the complaint with the court and have it served (by mail) on the opposing attorney, you will lose by default.  If that happens, you will need to file a motion to set aside the default.

At the law library, look for answer to complaint in the index of Pleading and Practice.  This will give you the general format for an answer to a complaint.  At the end of the answer is the verification which you sign and date under penalty of perjury.  The verification attests to the veracity of your statements in the answer.  File the answer to the complaint with verification and an attached proof of service with the court and serve it by mail on the opposing attorney.  You can use a court form proof of service or you can write your own.  If you write your own proof of service, it just says that you are over 18 and the attached documents were sent via first class mail unless stated otherwise to __________ (name and address of opposing attorney) on ___________ (date).  You sign and date at the bottom.  The date you sign should be the same as the date of mailing and the same date you file your documents with the court.