Leaving company after three weeks

Hi Experts, I have one query, appreciate if someone could help me. I have joined in one IT company, after working there for three weeks due to family emergency I came home and couldn't able to report anyone for two days. After third day I called HR, RM and informed that I won't be in a position to continue work. Later day I got call from another HR saying, I need to pay the three months notice or I need to serve the notice. Now today they sent me letter that, I need to come back and join the organization within the third day of receiving that letter, or else they will terminate my service. They can legally proceed in case of my non-compliance to their letter. Now I sent reply to their letter, saying that due to family issue I cannot be able to continue working there. One more thing would like to mention is, I got salary for that three weeks in the month end of that particular month. Could please anyone let me know, how to proceed in this situation.