I have a Kia Sportage from 2000 and since 4 months ago the frontal wheels dont work with 4x4 but the green light turn on can anyone help

Sounds like the front hub seals are out... sometimes they can dry up and seal poorly. There is a factory upgrade kit to replace them.

It is a standard procedure to replace them. Contact your dealership, if you purchased it from a dealer, then there is a remote chance they may give a discount to replace them... or do it for free :) If you bought it used, I'm not sure if the Warranty transfers.

I can help you if you are technically able to do the job. Have you ever removed a half-shaft?