Can't log into 1 of my characters

When do you say alts do you mean on the same account or different accounts? If you mean different accounts, then I think the same thing happened to me a while ago.

I was logging in to my 4 accounts like usual, and one of my chars would not log in. I closed everything and tried repeatedly to log that one char but it was no use. I had no idea if the problem was that particular character or some other problem because I always log my chars in the same order, and that char is always the third in line. I could not log that one, but I could log my fourth char just fine.

I then decided to check the multi-accounting tab and moved the order of login for my chars. I swapped the third char for the fourth and I was able to finally login all of them. I have no idea why that fixed it for me and I have no idea if this would work for you, but it's worth a try.

Old but gold!
Omg changing the order within the laucher worked ty