The easiest way I know of is replacing the password hash in the ilias.ini.php. Generate the md5 hash of a new password via the shell (if you are using Linux). Alternatively, you could also use an online md5 hash generator:
The resulting hash should be a 32 character hex-string. Open the file ilias.ini.php in your web root directory (exact path depends on your environment) and replace the value of the property "pass" in the section "[setup]" with the md5 hash. Then use your new password to login in the setup (/setup/setup.php).
I hope this helps.
echo -n "thisismynewpassword" | md5sum
The resulting hash should be a 32 character hex-string. Open the file ilias.ini.php in your web root directory (exact path depends on your environment) and replace the value of the property "pass" in the section "[setup]" with the md5 hash. Then use your new password to login in the setup (/setup/setup.php).
I hope this helps.