Hi viczack,
If you are using a Microsoft account, you may reset your password here.
However, if it's a local account and you’re using Windows 10, version 1803, and added security questions to your local account to help you reset your password, you can select Reset password on the sign-in screen. (This link appears after you enter an incorrect password.) Then, enter the answers to the security questions and choose a new password.
Please respond to this thread to let me know how the issue progresses. Similarly, if you have more questions, please inform me by replying to this post.