I have contributed NO answers that I know of and the 6 questions I have asked over the past year have ZERO answers.
In reality, you've posted a total of three answers since your account was on Ask Ubuntu. All three are deleted, as a direct result of review queue votes and flags against your posts about them "not being answers". (Deleted answers still count as answers!)
The three answers that were deleted do not fit into our criterion of "answers". In all three of your answers, you either are saying "I have this issue too" (which is not an answer), or are asking new questions which are basically the ones you already asked on the questions you had posted those answers on. If such questions are substantially different, you should post a new question, and if not, you should not post an answer to just state you're having the same issue and try and add different debug data (which may be relevant only to you).
As was already posted, the Help page indicates there are a lot of automatic filters. All of your posts have been delete-recommended voted in the Low Quality queue, and subsequently deleted as "Not an Answer" as a result of flags against your posts. The system acted as a result of this, and answer-banned you (meaning you cannot post answers) once it noticed the number of deletions of your answers outweighed answer contributions.
This quote, from the Help Center page about answer bans covers what an answer-ban is used for, and when they come into play, specifically where I add some emphasis below in regards to what I've observed here:
Stack Exchange has automatic filters in place to ban questions from accounts that have contributed many low-quality questions in the past. These filters help keep the quality of our sites high. The exact formula for the bans is not disclosed, but users are only banned if they have a significant number of heavily down-voted, zero-voted, or deleted posts. One or two bad posts will not cause you to be blocked from using the site.
From the same help center page, you can get information about how to resolve the problem. The first two in the bullet-points are relevant here, as is the whole section I just copied in:
How can I get out of an answer ban?
The ban will be lifted automatically by the system when it determines
that your positive contributions outweigh those answers which were
Stack Exchange cannot lift answer bans by request.
The only way to end a posting block is to positively contribute to the
site; automatic bans never expire or "time out". Begin by fixing your
existing answers; do not just post the same answer again or delete all
of your existing answers. All answers are expected to be useful to
future visitors, in addition to the original asker, so keep the
following tips in mind when improving your answers:
Answer the question. Do not post an answer simply to say "thanks" or "I'm having this problem, too"
Do not post follow-up questions as answers. Ask a new question instead.
Use correct spelling, punctuation, and grammar to the best of
Provide context for links. Link-only answers are not good answers.
For additional guidance, see "How do I write a good answer?"
The question on Stack Exchange Meta of "What can I do when getting “We are no longer accepting questions/answers from this account”?" is extremely relevant. Please read all of it.