Facebook Account Recovery: Lost Access After Password Changed

I bought a Facebook account from a friend about one year ago. After the purchase, the seller changed the password and I lost access to the account. Since then, the account has been offline for a long time and I have been unable to use it. I still have the old phone number and the old password that were previously linked to the account, but they no longer work for logging in. I have already tried the usual Facebook recovery options, such as “Forgot password” and receiving codes, but I have not been able to regain access. I am feeling very helpless because this account was important to me and I cannot use it anymore. I kindly request your support to help me recover access to this Facebook account using the old phone number and old password as verification, or to otherwise restore my ownership of the account.