Lufthansa — Extra penalty charged

I had booked a flight from Netherlands to India which I missed as the covid reports came positive which was completely shocking as i didn't have any symptoms. Hence the ticket went as no show, as when we contacted to reschedule Lufthansa clearly told us due to non availability, the same tickets can't be rescheduled also it was a non refundable ticket. So we didn't bother to cancel. Now when we are availing the return ticket which was booked together, Lufthansa had put a penalty for the no show ticket. I want the money back.