you need an 'anti-theft' code to reactivate the radio. whenever the electrical power to the radio is interrupted the system "thinks" that the radio has been stolen and it goes into anti-theft mode. if you purchased the car new, then you might find a white card about the size of a credit card with the owners manual or papers you received when you bought it. that card would have the anti-theft code on it.if you can't find the card, call the dealer you bought it from. they may have the code on file from when they sold the car. however, most dealers only keep records for 7 years and often in remote storage locations so don't count on them having the code.if you don't have the card, look inside the glove box for a white label about 1" long and 1/2" high. It may have two rows of numbers or just one. If it has two rows, the 5 digit number on the top is your anti-theft code. if it has one row of numbers about 9 charactors long, it is the serial number for the radio.if you have only the serial number for the radio, you can call any Honda dealer, give it to them and ask them to look up the radio code on their Acura system. each radio code is specific to the serial number of the radio; there is no 'universal' code.if you can't find the tag in the glove box, look under the rear trunk lid. if the car has an ashtray, pull it out and look at the backside or underside of the ashtray. the dealers put the tags in a variety of places when they did the initial inspection on the car.if you can't find the tags, then try this. with the key in the igntion switch and the key ON but the rado turned OFF, hold in the station select buttons number 1 & 6 with your right hand. then, while holding those buttons in, turn the radio ON with your other hand. You should see a series of 5 charactors on the display starting with the letter U and followed by 4 numbers. write them down. then the display will change to a second set of 5 charactors starting with the letter L and 4 numbers. write them down. then call the honda dealer and give them those numbers--those numbers are the serial number of the radio.if all else fails, the radio will have to be removed to get the serial number off of the manufacturer plate on the back of the radio. dealerships will not charge to retrieve the code for you but will charge to remove the radio.The NAVI code is a separate issue. You'll have to find the original code on the tag inside the glove box or elsewhere or otherwise you'll have to have the unit removed. There is no alternative on that one if it doesn't come back to life with the radio (it may work when the radio is reactiated).hope that gives you some direction. I think you'll be able to get the radio activated again. one note--you have 3 shots to enter the code correctly or you'll get an error message. if you get that, disconnect the negative battery cable and leave it off for 3 minutes to clear the error mode. then reconnect the cable and you can then enter the code.Hope that helps