Company issued absconding letter during sabbatical post maternity leave in 2012

Hi, i served in mnc from 2006 to 2012 during that period went on maternity leave in year 2010& asked for additional 1 month leave on medical grounds which hr rejected so no option went on sabbatical leave and submitted my company laptop in 2010. In 2012 i got absconding letter to which I talked to my manager and he asked me to avoid those.i documented the same and sent email to immediate supervisor but he didn't responded back.hr also marked FYI on that email and sent the same to manager but no response.instead thy issue no dues form next day marking absconding which i ignored as per manager discussion. From 2012 to 2021 i took a break to take care of my ailing mother who passed away in 2017 due to cardiac arrest. Post that i enroll in some professional course in 2018 so that I can start my life again & checked with organisation for reliving letter in 2021 they asked for outstanding and i paid those so that there will nothing be pending on my side to which they issued termination letter with writing absconding. I repeatedly sent them email showing i tried connecting with manager he didn't responded back and shared my maternity docs and my mother medical docs with apology that if it is miss at my end i apologize but all went unheard. Please advise how to pursue this again so that I can support my family and again start life with dignity which is spoiled bcz of some hopeless fellow in organisation that time