What to do with a thesis adviser that doesn't respond to emails or offer any help? I am a master student in computational mathematics, my thesis adviser assigned me a problem in a subfield that is outside his expertise. He is lazy and doesn't know much about the problem he assigned to me that later, after few months, I found that it is even not posed properly, I redefined it myself and of course, I am doubtful. I need an opinion, a discussion and whenever I request a meeting, I don't benefit from it and he says wrong information because he is ignorant about this area he got me in and he avoids me intentionally because he knows I will ask him and he doesn't have answers. I stopped visiting him, he and the other adviser because I don't benefit from the stupid meetings. 

Now, even that I am working all by myself, I am sending him emails and he ignores me completely. We are now in quarantine so I can't go to his office even.

Now, what do you advise me to do?
I really came too far now. I can't quit. I have tried to ask other authors who work in the same area, no one responds. 
Should I continue anyway by myself? or not?
You are a bit stuck. It would be a shame to abandon work already done if it shows promise of successful completion. 

But there are really two things that you should require from your advisor. First, they need to approve of your thesis when complete. Second they need to write you a good letter of recommendation for the next stage of your career. 

Everything else is nice, but not essential. If you are capable of doing the work on your own and can achieve those two things, nothing else will matter. 

I'm more concerned, actually, that no one responds to your request for help. Perhaps if you take a different approach with external professionals it would be more successful. My preference would be short introductions and very simple explanations about what you are working on. Make it easy for anyone to make the first response. If you send too much it is more likely to get ignored. 

Quit and restart elsewhere only if no other option is open to you. Given the current pandemic (early 2020) no one will think poorly of you if you need to start over. It will delay your career, but not necessarily end it.