The key needs to be re synchronised to the car. The method used depends on the make/model/year of car, which you have not given.
The instructions for posting a question are quite clear-
(Add all the detail you can. Include the item's name, make and model details. The more detail you add the more likely it is that others will be able to help you.)
fred
December 2009
howtomendit.com for free repair help, information and advice.
