Happy New Year Julie...
Car radios have an anti-theft security feature - if the power is removed then the user has to put in a special code to get them working again. You can often find the code in the handbook of the radio but many people no longer have their handbook.
You will do best to ask another question - say the year, make and model of the car and as many details of the radio as you can - brand name - model name - model number and serial number. You may need to remove the radio to get the details.
Somebody may be able to help you - the local main dealer for the make of car may also be able to help too.
Good luck..., January 2015
