For those, who are unable to sign into aol desktop. you should check the screen name properly. most of the time, people are unable to type the correct screen name (Which is also known as username) and password for their aol account. that’s why they go through such kind of problem.
If you aren’t sure about the username and password. you always have an option to reset the AOL screen name & password. so you can go ahead and reset it any time.
To reset the screen name and password, you just need one recovery option to verify yourself.