If you really have read it then you should know the answer. You can prove that you own the account by other methods if you can't sign a message using your Bitcoin address though there is a little chance to be entertained. If you can sign thru that altcoin addresses then try with the same format you see in that link and attach the link to where you posted it.
I very rarely recover accounts if you can't prove ownership as described above. There are alternative ways of proving ownership, but they take too much time. If I point you to this thread, you can't prove ownership properly, and then I ignore your future PMs, this means that I'm not going to recover your account. Create a new one.