Password are case sensitive so please look all the keys on the keyboard is working fine, use on screen keyboard to login, make sure caps lock is not on, sometimes num lock key is off, now still password is incorrect then check if it's Microsoft account or local account, in case of Microsoft account use pin to login instead of password. You will find pin and password option under sign in options.if pin is not set up then make sure you are online while entering the password. If still password is incorrect then you may reset the password for microsoft account , obviously you have to use another device to reset the Microsoft account password, visit the below link to reset the password.
Enter your email and Click on forgot password and reset or your password.
In case you are not using Microsoft account then in local we don't have much option. You might have reset the system which will reinstall the windows and you will lose all the data .
Steps to reset
On the login screen you have to press and hold the shift key on the keyboard and while holding shift key click on restart from the power icon on the bottom right corner of the screen, it will take you to windows recovery screen , click on troubleshoot and then you select reset or factory image restore to reinstall Windows, once done setup your system and start it from scratch.
Reset steps are applicable for windows 10 users.
Thanks, but it's not a microsoft account.. it's a local login password, so any help?
For local user account, PassFolk free tool is the a nice option: https://www.passfolk.com/
You can make a password reset with this tool (USB or CD). Then use it to remove local account password.