There could be a few reasons why your password is being rejected even if you're sure it's correct. Firstly, check if you're using the correct username or email associated with the account. Sometimes we may use an alternative username or email that we forget about. Secondly, ensure your caps lock key is turned off as passwords are case sensitive. Thirdly, check if your password contains any special characters like #, @, etc. and whether you're typing it correctly. Lastly, try resetting your password to see if there have been any security breaches or unauthorized access to your account. If the issue persists, it's recommended to contact the support team of the application or website you're trying to access for further assistance.