As the FAQ is currently written, the only way to lift a post ban is by fixing your existing posts - including deleted ones.
However, various users - mostly high rep users on MSE - claims that you're allowed one question every six months if you're banned from asking. And if you managed to ask a well-received question, your ban may be lifted automatically. If you failed again, go wait another six months.
I'm curious why this information isn't added into the FAQ. Is it wrong? Is there any special reason not to add it?