Invalid termination

I was working for a company and I had signed a contract with them and I was asked to submit my orginal marksheet as a security deposit. Due to my health condition I informed my team lead and took a day leave and the next day I was removed from the group and I was told I'm being terminated and they requested to submit the office assets. Then I asked them to send out an email stating my termination and assurance of the salary for the working days, initially they refused to send email and insisted me to submit the assets. I clearly told them without the email and assurance of the salary I'll not proceed further. Then after two weeks they sent me an email stating I was terminated and they won't pay my salary for the working days, I asked them the reason for termination and they're not giving any valid reason and I see they're giving reasons stating unplanned absentism which not true as I have all proof that it's was approved by the team lead. Then later they're giving invalid reason and nothing is true, later they concluded saying they won't pay because it's a red exit and thertening me to submit the office assets. I have informed them that I'll not submit anything untill I get paid for the working days, as I'm very sure my termination is invalid and not appropriate. I joined the company on 1st November and my termination date is 17th December and in this tenure I only had one day leave which was well informed and approved. But the the company is terminated me for unplanned absentism which I don't understand and it's a lie. Now I'm in suitation I'll only submit the assets after they pay me. Please help me with the legalitys/suggestions as I feel this company is trying to manipulate and mentally disturbing me.