Apple ID cannot be used to unlock this iPhone.

Hi, I haven't used an iPhone for a long time, now I needed it, 
I entered the password for my account, and a message appeared stating 
that this iPhone could not be unlocked, although all the data was entered 
correctly. After looking for information on the Internet, I used the solution, 
but my device was not in the list of devices on the icloud website. What should I do?