You've been answer-banned.
Fortunately, it is usually possible to get un-banned. The main thing to do is improve your answers. This is sometimes possible even after they have been deleted. I've looked at a couple of your answers that I think you might be able to improve, and if you have deleted answers you've edited and want considered for undeletion, I've given some suggestions about how to go about that.
But first, if you have not yet done so, please read all this:
Those official resources are the most important sources of general information for users who have been answer-banned. However, I also suggest taking a look at:
You mentioned you tried to improve some of your deleted answers. Especially if you did this after they were deleted (but took no further action), it's possible that your improvements are good but very few people have noticed them. As far as I know, when you edit a deleted answer, no one is automatically notified.
So if you've improved deleted posts, considered any concerns about your posts that people may have expressed in comments, and are confident they now make good answers, you can flag them for moderator attention and write a custom flag reason explaining why you believe they ought to be undeleted. However, since you have this meta question, I suggest adding links here to any deleted posts of yours that you've edited for improvement and believe may be appropriate for undeletion (assuming you have the links). Most users won't be able to follow those links to see your posts, but users with 10,000 rep or more (and moderators, of course) will be able to view them.
Currently, your two (non-deleted) answers are on Is there a way to increase the screen saturation on Ubuntu? and My var/log folder is taking too much space. If you're interested in making those better, I think you may be able to.
Even when the OP doesn't use an answer, it may still help the community.
You said, "a question was solved just by comments, simply ignoring my answer." I'm guessing that's My var/log folder is taking too much space. I can't quite tell if it was really solved, but people's problems do sometimes get solved in comments. (What that happens, the solution should almost always be posted in an answer -- and sometimes, should've just been posted as an an answer in the first place -- but I guess that issue is beyond the scope of this meta question.)
However, that doesn't usually mean it's not valuable to improve your answer, because answers on Ask Ubuntu don't exist only, or even necessarily primarily, for the benefit of the one person who asked the question. Ask Ubuntu is one of the main official community support resources for Ubuntu, but it is also, as the tour page puts it, an effort "to build a library of detailed answers to every question about Ubuntu." Therefore, if you think you can make your answer better, then even if it doesn't help the original poster of that question, it may help someone else.
In this case, your suggestion seems eminently reasonable to me, but it's only a little bit useful without expansion. You make two points, each of which could be expanded with detailed instructions:
You recommend booting into a live environment to delete the log files. Could you expand that by explaining exactly how to do this, step by step? In addition to describing what to do, can you include specific commands you suggest running? Can you include screenshots that show exactly what you suggest doing?
(You should, of course, only add images if you think they really make your post better. For example, there's no need to show an image of text in a terminal. And you should make sure that the images you use successfully illustrate the topic you're explaining. For example, sometimes it helps to crop a screenshot and/or draw a freehand circle to highlight something important.)
You recommend investigating why the log files have expanded so much, but you don't give any explanation, tips, or instructions as to how someone might go about figuring that out. So if you have recommendations for how to look into that, you may want to consider adding them to your answer.
It's often helpful to update your answers with new information and details.
You said, "a question was not solved." I'm guessing you're referring to Is there a way to increase the screen saturation on Ubuntu?.
In your answer, you recommended attempting to calibrate monitors in System Settings > Color. Later, in a comment, you mentioned that the option to calibrate, which was not usable for the OP, was not usable for you either, but that there was another procedure that worked for you. You did not describe this procedure in detail or add any information about it to your answer. From your description, it's not obvious to me quite what you are recommending.
So I suggest expanding that answer with a detailed description of all the actions you think the original poster, or someone in a situation like theirs, should take. If there are written instructions shown in System Settings (I'm not sure if this is what you meant), then you could put something about that in your answer, explaining how to do what they recommend, and also quote some or (depending on their length) all of them. Either way, it's clear you are saying that there is something of potential value in System Settings, so I recommend being specific about that, and also, if you think it is helpful, including screenshots showing how to get to the right place in the settings and what to do once there. Examples might also help.
Although I am not sure because I do not fully understand your comment -- and I suspect this is a problem others have had, too, which might be why that answer hasn't gotten any upvotes -- it seems from what you said that you know how to solve that particular problem. So I think that if you edit your answer to teach us how to do what you've successfully done, then it would be a much better answer. This would have several benefits -- for example, people with that particular technical problem could understand and solve it! -- but one of the benefits might be upvotes on the answer, which could lead to the Stack Exchange software lifting your answer ban.