There can be numerous reasons due to which you might be facing issues signing into your account. You may have forgotten your account password or maybe the CapsLk key on your keyboard is active or maybe your account has been hacked. As there can be multiple possibilities behind the login error, it is suggested to make sure of the following before following the further steps.
Make sure you are entering the login credential for your account correctly.
Make sure that the CapsLk key is not enabled on your keyboard.
As the modern web browser comes with an “autofill” option, make sure that your browser is not auto-filling the password that you have already changes. In such a case, you will need to update the password in the auto-fill settings of your browser.
If your Comcast email account is connected through an email client, make sure that it is configured with the correct email settings. Alternatively, you can try accessing your Comcast account using your email account instead of accessing it through an email client.
Make sure that your Comcast modem or router is connected properly.
Try accessing your account through another browser, computer, and internet network.
If even after following these steps you are unable to access your Comcast email account, then perhaps, your account has been hacked. In such a case you will need to reset your Comcast account by following the steps provided below.