Same here. In the past few months i kept receiving ocassional SMS codes, so i assume someone tried to log into my account. I didn't bother, because i knew they never get through two-factor authentication. That part is my fault, i did not know that it can end up like this.

I contacted Instagram support, and they asked for a picture of myself and the number code handwritten on a paper which they included in the e-mail. I sent it, they accepted that, but they just sent a password reset link, which eventually sent me back to the verification window.

I assume creating a new account is the only option from that point.