What happened to my account?

So some time ago I've had problems with one of my accounts, because I couldn't log in as it has been hacked. After that it has been used 2-3 more weeks and after that I wasnt able to find it anymore. The Chat in the DM's turned into "Instagrammer", all the pictures under the certain hashtags disappeared. At first I was sure that it has been disabled due to the hacking or something, because this happend to me before. The thing I was wondering about was, that almost instantly after that, some cunt directly used the name for a new account. I dont understand that, because once an account gets disabled, the name is destricted, right? Was the account completely deleted? What happened?
I can't even fill out the Instagram Form for lost accounts, because there you have to enter the name of the disabled account, but as I said before the account name is used by a new account..
I have the OG Mail and so on, Ive already uploaded a selfie of me at some time, because people said that would help to get you an acc back at some time..

What happened to the acc? And what can I do?

This happened to me when my account got hacked as well.

What they most likely did was change the name of your account, either deleted or temporarily disabled it, and then used the name to create a new account.

Just submit a hacked account form to Instagram. As long as you have access to the email that was originally used to create the account, and it was just temporarily disabled and not actually deleted, you'll get it back. It took about 3 weeks from the time I submitted the first form to getting my account back.

They just deleted your account.