1998 Mercedes Benz C180 radio code

after changing battery car, i had to restart my radio by writing a code. i tried few code that i find on internet but nothing worked. and after all this i opened the mercedes guide which was always in my car but never use it cause it is in german. in that guide i found the right code but till now could do nothing. it always says wait and i wait for hours but the radio does not work. pls can u help me to make it work again? thank you