Hi Kunal,
First of all, I would like to apologize for the delay in responding.
This issue might have caused due to many reasons, such as when there is an updates that needs restart or when you change the password from the website and then not getting synced. Before we proceed with the troubleshooting steps, I would like to know some
information about this issue.
1. Have you changed your password recently?
2. What happens when you enter the password?
3. Do you get any error code or error message? (Are you getting the same error as Mike received?)
4. Have you tried to sign in to Microsoft Account on the website?
In this scenario, as a first steps I suggest you to restart the computer and then try to sign in and check if you are able to sign in.
If you are still not able to sign in then try signing in to the Microsoft Account from the website and check if you are able to sign in there. This is to check if the issue is caused due to any Account or account password related issues.
If you have forgotten your Microsoft Account password, then you may try the steps in the Microsoft Help article that Ganesh has provided in his response.
Please reply with the status of the issue so that we can help you better.