I suspect my brother is struggling with his mental health. What can I do?

My brother just turned 30 and I'm two years older than him. Growing up he was always the smartest kid with good grades while I was a terrible student and people never had faith that I would succeed in life. My mom was always very proud of my brother's good grades and always insisted with him in pursuing some type of engineering. So he did he studied computer engineering for 3/4 years and after some time got a job. He stayed on the same job for approximately five years, had a good salary, moved to an apartment and was living independently. One day out of nothing he tells me he's going to resign next month. I was very surprised about this sudden decision and asked why and if he already had any other plan. He said he wanted to take a break from work, learn something new, upgrade on his career and find another job in four months. He ended up moving back to my parents house and been there for more than a year now. I live in a different country and don't go home very often but last time I went home I was completely shocked with his behavior. How can a 30 year old Man sleep every day until 1PM, shower every other day and spend his day playing video games? He rarely leaves the house and we never heard about any girlfriend.
My parents are pretty upset and disappointed with the type of person my brother turned into but he's a mommy's boy and my mom is always very soft with him and accepts any excuse he comes up with. As I mentioned on the title of this post I suspect my brother is struggling with his mental health and I do not agree in pressuring him as we don't know exactly what is going on his mind and what kind of thoughts is he having. I fear he might hurt himself or do something crazy if he feels pressured and overwhelmed. I really want to do something but I don't know what to do.

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I always try to ask him questions on what's going on and he always says everything is fine.
Often when we speak on the phone he only gives one word answers to my questions and doesn't seem to want to talk about it he seems to lack motivation and ambition and it hurts to see him that way because I know how smart he is and how much potencial he has. My parents told me many times to see what's going on hoping I can find a solution for what's going on but I really don't know what can I do.
I suspect my brother is struggling with his mental health. What can I do?
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