Juan Jose Rebaza:
If you created a file and created a new account and password, it is possible you did not allow access to any layout in the database file. Use the [Full Access] password to open the file and check the new account settings. The [Full Access] account is "Admin" with a blank password (unless you also changed the password).
Thank you very much, I also called File Maker and gave me same solution. Luckily it was a bran new database and the Admin user works...
In the future, you should save a copy of the file just before making major changes to manage | Security. That gives you the option to trash the file and open the back up copy if you accidentally lock yourself out of the file.