Termination - if the employee is not ready to serve the notice period then what will be next option?

Dear All, I want an opinion from you. I was working in an organization for last 4 years and in August month I resigned from my position. I was unable to serve the notice period same I mentioned over the email. They didn't respond me in first 15 days and then when I asked for reply then I got revert notice period will be mandate which I couldn't serve.
I want an opinion like is there any other way if the employee is not ready to serve the notice period then what will be next option?
Can they directly terminate the employee? And in letter they mentioned employee was not contactable but employee was talking over the mail, nobody called from hr team.

Please help as i don't know about the rules asking as an opinion.
Thanks

The option in cases of incomplete serving notice period is to buy out the remaining period provided the employer agrees to it. It is at the discretion of the employer to insist on serving the notice period fully or accept the payment for the days not served. In case you have not offered to pay them already, you may consider making the offer or even propose to get it deducted from the dues payable to you. You have not mentioned the notice period and how much you served. You can point out that you have been continuously in touch with the authorities, so the conclusion that the employee was not contactable is totally unwarranted and seek a review thereof. You are on a strong point here and so can threaten them with legal proceedings in this regard.
The advice is to approach HR/Departmental authorities for a review of the position and try to persuade them.