During a fresh install the first created user should be the admin user, you should be able to login with the login name or the email address of the user; if not then I'd recommend re-running the install script after clearing the database as you have an empty forum. If you're trying to redo the install please always start with an empty database.
Be sure you're not using capital letters, and that you're trying to login with the login name or email address and not the display name.
Its obviously worked before as you had a fully running install that you had edited the script files. We do not support modded forums as we have no clue as to what you could have modified.
This is a user to user forum, you can obtain official support from the support desk should you need hands on support.
