Unable to login into website after installing and setting up itweak_login
After reviewing that module's code, I have to agree with @Aboodred1 in his comment you can disable the module from the database for several reasons (which I'll address on the module's drupal.org page rather than this site because I don't think this site is the appropriate place to do so). This is not the preferred or recommended way to do things, but it seems like you might have no other choice if you've already installed it.

Method 1


BACK UP YOUR DATABASE
If you don't feel comfortable directly accessing your database, you should be able to log in to your web server and delete the itweak_login module directory (usually located inside sites/all/modules) and everything inside it. This should at least give you access back into your site. If that doesn't work, or if you do feel comfortable accessing/modifying your database directly, here's an elaboration on the aforementioned comment:


Method 2


BACK UP YOUR DATABASE
Log in to your web server and open the settings.php file for your Drupal installation (usually located at sites/default/settings.php)
Find the line that looks like this:

$databases = array (
  'default' =&gt; 
  array (
    'default' =&gt; 
    array (
      'database' =&gt; 'mydrupal7database',
      'username' =&gt; 'mydatabaseusername',
      'password' =&gt; 'mydatabasepassword',
      'host' =&gt; 'localhost',
      'port' =&gt; '',
      'driver' =&gt; 'mysql',
      'prefix' =&gt; '',
    ),
  ),
);

If the prefix line is empty (as it is in the example above), continue on to number 5


If it's not empty, e.g. if it looks something like this: 'prefix' =&gt; 'drupal7_', then replace the word system in step 7 with drupal7_system (in other words, add the prefix to the the word system)

Log in to your database if you're not already there
Select the database used for this particular Drupal installation (using the example above, you'd select the database called mydrupal7database)
Run the following SQL statement:

UPDATE `system` SET `status` = 0 WHERE `name` = 'itweak_login';



Note: after you disable the module in the database, you should be able to access your site again. At this point, I'd highly recommend uninstalling it by visiting the module uninstall page (admin/modules/uninstall), and then after it has been uninstalled, remove it from your server altogether (using Method 1 above).

Hope that helps...

:)