Security codes?

could this be caused by a security code, maybe because some fuses were pulled that supplied power to the radio?

I meant to say the radio will not work, and when a tape is put in, it ejects right away. Is this some sort of security theftlock? The radio fuse was pulled at one point. The display does not show locked or any other abnormal display. Is a simple reset all that is needed or is there a security code unique to this unit. I called the dealer, they said older Hyundais had theft codes, but not the later ones. If I do find a code, how do I enter it? Thanks