Password to account issue

Just today, I couldn't seem to access one of my accounts. I'm 100% the old password was correct and I just logged onto it yesterday and it was fine. I tried multiple times, both in log in screen and the official website. But it keeps prompting me that it's incorrect. I finally have it reset and there are no messages that show password has been reset by someone else in my email account. I checked the account activities by IP and it only shows 3/3 IPs which are all from me. Afterwards I used Nexon's automated password to log on. Everything's secure and not missing. Later, when I try to change my password, I ran into problems trying to change again, saying that my passwords don't match. I even copy and pasted the new passwords and it said the same thing. Only reason I can think of are because of the special characters I use in succession. (non extended ascii though, just shift + key combinations which you can input on any typical keyboard) But funny thing is, I used the same symbol across few other accounts but they still work fine. It's just weird how it got locked up one day out of nowhere, sort of like the Fort Knox method, except unintended.