Reigned from the job and company is not reliving on time

I reigned from the company on 22/Dec/2021 due to my wife's pregnancy related issues. From March 2020 company permitted work from home due to Covid. After I resigned HR send me an email saying immediately report to office and no work from home permitted in notice period. They asked me to report to office on 4th Jan 2021. I replied that it is not possible to join on 4th due to wife medical condition and I went and reported on 11th Jan. Now they are saying my notice period started from 11 January 2021 not from 22 December 2020. I didn't stop doing my duties afte I resigned. Now they are holding my salary from December. In between in January I took 2 days leave also. HR is not even saying about my relieving date. Please let me know company is doing legally or illegally. If they are not reliving me on 25 Feb (included 2 days leaves), then can I leave from the company. I heard this company sending notice and asking very big amounts to the employees who all are not completing notice period. Asking amount in the name of project loss.