Weird login fail

Hi, I have a problem, which I am really worried: this problem started to appear from nowhere yesterday evening. This problem is the following: whenever I try to log-in to my account (Minecraft Launcher, Minecraft website, etc) it says that the e-mail or password is wrong. I don't understand why it says that, because I literally changed my e-mail and password several times, and I can say that the e-mail and the password is correct, not wrong, as it says. Also, I tried to log-in (I found this issue on my PC) on other devices like tablets and phones, but there wasn't any log-in issue, so it might be my PC that causes the problem, but I really can't explain how and why this is happening. Please help me, I don't want that the thing gets critical. Thanks.