i need the instruction of how to reset the radio code for S90 1997 after changing the battery.

First of all, :00000732: to the forum. Generally you will get more hits if you post your message in the appropriate forum. Now to your specific question. There should be a four digit code in your owners manual packet, usually on a credit card sized piece of paper. If you have that then all you need to do is power up the radio and punch in those numbers using the preset buttons. If you don't have or can't find that card you can use your VIN number and call the nearest dealership and get the code. Hope this helps.