That's unfortunate, yes there are some ways to brute force your wallet, only if you knew and remember partial/some details of the password, but on your case seems you totally forget about it, try to remember it, coz bitcoin core will not require and ask a password if you did not set a password on it AFAIK (correct me if I'm wrong though).
BTW this should be moved to
Bitcoin Technical Support to get more attention from devs and people who might try to help.
I open the wallet as it does not contain any password while I am surprised that it asks me for the password, so I do not remember anything except that I did not make a password on purpose. The only possibility I suspect is that asking for the password is an error.