If your talking about check engine light the only way to reset the codes for those is by a OBD II (On Board Diagnostics) scanner, you can buy one at any auto parts store, but if you do not wish to...
If your the actual owner of the car and it has the manuals, there's a 4 digit code in one of the Kia manuals for the radio, it's usually something like 1212 but if you enter the wrong code too many...