Notice Period Pay

Dear Seniors,
One of my friend has resigned from his services without serving the notice period but he informed all the seniors and managers before leaving. He left on the same day he resigned.
Now he has already worked for 24 days before giving resignation. As the company is not ready to give him the relieving and exp. letter, he is ready to pay on lieu of notice period.
Notice period was of 1 month.
As he has not got any salary for the 24 days he worked, what would be the amount he needs to pay to the employer.
His salary was 13,000/- per month.

Dear
management can deduct one month salary .let them make full and final where he will be paid for 20 days and deduction will be for
30 days .so whatever balance of 6 days will come ,he should make the payment to get relieving letter