Login not working (root password I always use results in "Authentication failure")
 

First off, any help is very much appreciated.

I just got a used ipod nano and needed iTunes to add/delete songs. So I was in the process of trying out some software called "playonlinux" and so far as I can tell it installed properly without a hitch. But when I typed "playonlinux" in the terminal it kept telling me something about being unable to login as root or sudo.

So I created a new user called test1 with a password of test1, but it keeps telling me something about ...ICEauthority... when I try to login to it. So I went back into my running root account by logging in as I always do, by typing in "root" and "[password]" whenever I want to login or unlock my computer. My usual username (root) and password worked, and I tried creating a new user named batman with the password being robin, but that username doesn't appear at my login screen, only "test1" and "other" do. Everywhere I look is telling me solutions involving terminal, but I can't figure out how to get to a terminal window in the first place without first logging in, which I'm totally unable to do.

Summary:
added user test1/pass test1, using terminal while logged in as root;
was unable to log into test1 due to something ICEauthority;
logged back into root from the kali gui login screen;
attempted to create user batman/pass robin, using terminal while logged in as root;
found no way to login to batman from the switch-user login screen, and in the process of attempting to log back into my root account I find that my usual login for "root"/[password] don't work;
I now know of no way to get my computer working again other than to do a full reinstall;

I'm now sitting here with an ipod I can't update and a computer I can't even log into.

Again, any help is very much appreciated, I will continue looking for solutions in the mean time but if anyone knows how to solve this problem please let me know. At this point I'm guessing I'm going have to resort to a complete re-install but would greatly prefer an alternative solution that would allow me to keep my files.

Sincerely,
Parker

Lots of things going on here...could you please clarify your question? So far I'm identifying three different potential questions:

1) How can I use an iPod in Linux
2) How do I handle these errors I'm getting in playonlinux
3) How do I add a user that can log into the system

Which one is the topic of this thread? It would be best to pull the unrelated information out and just focus on the question at hand. If you have multiple unrelated questions, it's best to split them up into separate threads.

As for accessing a terminal without logging in to the DE, use Ctrl+Alt+F2-6

Also, you should never be logging into the DE as root.

Sorry, the ipod reference was backstory explaining how I got to the situation I'm currently it, I wasn't sure if it was relevant at all but I thought the "playonlinux" install process might have somehow had something to do with it.

But the only question I'm asking here is "How can I log back in to my computer without reinstalling kali?"

Update: I tried recovery mode (I think) and at the end of loading a bunch of text it asked me for login information and I figured out the password. No idea how it became the password, but I'll be excessively careful in re-applying my previous password.

So, problem solved, but thank you sooooo much for your very timely offer of assistance, seriously, thank you.

Sincerely,
Parker