I was once hacked and was assisted in recovering my account by @someguy123. He even discovered how I got hacked, and is the most likely source of the best advice and assistance I can think of.

I sure hope you are able to recover your account, because I have greatly benefited from your counsel and considerations. Even if you cannot recover your account, you can make a new one and continue to participate on Hive.

Perhaps you at some time or another changed your keys, and have forgotten the event. I have done similar things, and while in the process of fixing things, forgot to write down what I had done.

What account you have specified as your Recovery Account is important. I will also ping @antisocialist here, because he is extremely wise and knowledgeable in all things and all ways, and can probably fix whatever is wrong, or at least point you to the sites where you can ascertain your recovery account, when you last changed your keys, and similar important information that may well prove key to resolving your challenge.

I wish I could do more than ping better men than I, but this is honestly the best assistance I can provide off the top of my head.