My Mom Has Mental Problem/Disorder!

It's been around 18 years since she started having problems, whenever i ask my elders about it they say it might have developed during the delivery of the baby, i really don't understand the reason behind her behaviour, she doesn't wanna work and she sleeps almost the entire day, I'm worried because she's starting to put on more and more weight day by day and my father completely lost his hope of treating her condition because there were times when she was forcefully taken to the hospital and she used to get crazy! and used to deny that she has any kind of illness/disorder and this is more worrying when it looks like she has no role in my life!, She sleeps all day and laughs sometimes without any interaction/any reason and says she doesn't wanna work and she's unable to get up in the morning, everything's fine about her except her excess sleep, laughing of no reason and when asked she says she has recalled some joke! And not working/less work throughout the day! Pls Help!