You have issues logging in into your account? Follow this to (maybe) solve this issue...

It says that my user doesn't exist, but it does.

This message shows for a variety of reasons, such as if you try to log into an admin's account. The most common reason is if you have enabled email only login.
This setting can only be enabled if you have an email address on your account, so if you don't, then it's not enabled.
If you have an e-mail address linked to your account, try logging in with it in place of the User ID.

I forgot my password and don't have an email address on my account.

Unfortunately, your only option is to contact an admin, they will have to give you a password reset link if you can prove that it's you.

I'm being hacked, help.

If there are others in your acount, then change the password immediately. It will log anyone else out.
If your email address was changed or you don't have one, then contact an admin ASAP.

Generally speaking, you should use a random password and keep it in your notes or something.
An option that may help the security of your account is to choose to only have it logged in via your email address. Then, if your email address isn't public, that's the only way to log in. With the option enabled, nobody can even try to log in to your account if they only know your public username.

I'm getting a message saying "Your password must be reset"?

This message appears rarely, in cases where your account doesn't have a password or there's another problem with it.
You will need to either reset your password via email, or ask an admin to reset it. Sorry about that.