Forget password and username, but remember ip.

Hi, I have a server problem. I do not remember my username or password. I only remember the server address: 123_play.aternos.me
I have evidence that I was playing on this server and had access to it, but I will show it to you when you want. This is a movie that presents my world and this movie is on youtube.
I do not remember if this world is still there, but I still want to recover this server. Username MIGHT be KacPRO or HD555. This server is belong to my friend, but he wants this server too. Please help me!
PS. I have translated this text into Google Translate because I am from Poland