I replaced Drupal 7.33 with WordPress now I'm trying too get drupal back

1. I installed wordpress in the same directory as my drupal install.
2. I have replaced the wordpress index file with he drupal index file and am now getting a error
messagePDOException: SQLSTATE[HY000] [1045] Access denied for user ‘myusername_drupal’@’localhost’ (using password: YES) in drupal_get_installed_schema_version() (line 155 of /home8/myusername1/public_html/includes/install.inc).

Can anyone help me with step 3?

Drupal version: 


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