I imagine your include statement above is making the connection for you?? I notice you have the variables for the connection, but are not making a connection (unless it is done in the include statement).
Also, in your
$password = mysql_query("SELECT id FROM dbname WHERE password LIKE $result") or exit(mysql_error());
you are using the $result variable before you have an a value for it. Don't you want to look up the password by the e-mail address and not the $result variable.
Also, should admin__db.php have 2 underscores as it is appears to have in your code?
Just a few things to check..
I would first recommend you verify your connection by posting your results to a simple query to the page.. To be sure you have a connection. You may also want to echo your query statements to the page as well -- so you know they are what you truly want.