Dear Sir, I am an indian working in kuwait a...

It is illegal for the employer to hold your passport, by which you cannot leave the country.Therefore, you should file a complaint at the Labor office and report that your passport is being held by the employer. This action has to be taken by your lawyer. Then, you have to take a copy of the complaint and to go to the Immigration office, so that they stop counting the overstay fine.
As in regards of how long does it take, it depends on the urgency of the case, but in ordinary cases it is done within two months, as it is a labor-based complaint.
Finally, please be informed that your lawyer can make it quick, but it depends on the procedures and their time of action