hello and welcome to HCM forum,
according to history presented by you, i would like to inform you that your dentist
is right when he said that your lateral incisor is dead, it means that due to trauma the blood supply to your tooth has been cut off which has resulted in a discolored tooth, you have not mentioned if there is any associated pain or swelling.
i assume that the tooth is symptomless, there is a definite treatment for your tooth,
its root canal treatment
, and following the root canal , a crown will be cemented over your discolored tooth to make it look natural.(matching the color of the adjacent teeth).
i would suggest get the treatment done soon before its too late,
i wish you good health.