Unfortunately "I cannot login" covers a lot of territory.

If you are still having difficulty, please add more detail to help us better understand. Thanks.

I set a Mozilla Password but not recognized so no email !

I set a Mozilla Password but not recognized so no email !

You should start a new Question rather than ask on someone else's existing question.

You may be under a misconception - your Mozilla password allows you to use this web site, but it has nothing to do with receiving or sending email. To use Thunderbird, you must set it up to connect with your existing email service (Gmail, AOL, Comcast, Charter, etc.)

Maybe I don't understand your issue. Please start a new topic and provide more information (the name of your email service, how you set up Thunderbird, your computer platform, any error messages, etc.)