Assuming you have access to your mysql server, then:
<code>
INSERT INTO `LUM_Role`
(`Name`, `Active`, `PERMISSION_SIGN_IN`, `PERMISSION_HTML_ALLOWED`, `PERMISSION_RECEIVE_APPLICATION_NOTIFICATION`, `Permissions`, `Priority`, `UnAuthenticated`)
VALUES ('Unauthenticated','1','1','1','1','a:32:{s:23:\"PERMISSION_ADD_COMMENTS\";N;s:27:\"PERMISSION_START_DISCUSSION\";N;s:28:\"PERMISSION_STICK_DISCUSSIONS\";N;s:27:\"PERMISSION_HIDE_DISCUSSIONS\";N;s:28:\"PERMISSION_CLOSE_DISCUSSIONS\";N;s:27:\"PERMISSION_EDIT_DISCUSSIONS\";N;s:34:\"PERMISSION_VIEW_HIDDEN_DISCUSSIONS\";N;s:24:\"PERMISSION_EDIT_COMMENTS\";N;s:24:\"PERMISSION_HIDE_COMMENTS\";N;s:31:\"PERMISSION_VIEW_HIDDEN_COMMENTS\";N;s:44:\"PERMISSION_ADD_COMMENTS_TO_CLOSED_DISCUSSION\";N;s:25:\"PERMISSION_ADD_CATEGORIES\";N;s:26:\"PERMISSION_EDIT_CATEGORIES\";N;s:28:\"PERMISSION_REMOVE_CATEGORIES\";N;s:26:\"PERMISSION_SORT_CATEGORIES\";N;s:28:\"PERMISSION_VIEW_ALL_WHISPERS\";N;s:29:\"PERMISSION_APPROVE_APPLICANTS\";N;s:27:\"PERMISSION_CHANGE_USER_ROLE\";N;s:21:\"PERMISSION_EDIT_USERS\";N;s:31:\"PERMISSION_IP_ADDRESSES_VISIBLE\";N;s:30:\"PERMISSION_MANAGE_REGISTRATION\";N;s:21:\"PERMISSION_SORT_ROLES\";N;s:20:\"PERMISSION_ADD_ROLES\";N;s:21:\"PERMISSION_EDIT_ROLES\";N;s:23:\"PERMISSION_REMOVE_ROLES\";N;s:28:\"PERMISSION_CHECK_FOR_UPDATES\";N;s:38:\"PERMISSION_CHANGE_APPLICATION_SETTINGS\";N;s:28:\"PERMISSION_MANAGE_EXTENSIONS\";N;s:26:\"PERMISSION_MANAGE_LANGUAGE\";N;s:24:\"PERMISSION_MANAGE_STYLES\";N;s:27:\"PERMISSION_ALLOW_DEBUG_INFO\";N;s:27:\"PERMISSION_DATABASE_CLEANUP\";N;}',0,'1'),
('Banned','1','0','0','0','a:32:{s:23:\"PERMISSION_ADD_COMMENTS\";N;s:27:\"PERMISSION_START_DISCUSSION\";N;s:28:\"PERMISSION_STICK_DISCUSSIONS\";N;s:27:\"PERMISSION_HIDE_DISCUSSIONS\";N;s:28:\"PERMISSION_CLOSE_DISCUSSIONS\";N;s:27:\"PERMISSION_EDIT_DISCUSSIONS\";N;s:34:\"PERMISSION_VIEW_HIDDEN_DISCUSSIONS\";N;s:24:\"PERMISSION_EDIT_COMMENTS\";N;s:24:\"PERMISSION_HIDE_COMMENTS\";N;s:31:\"PERMISSION_VIEW_HIDDEN_COMMENTS\";N;s:44:\"PERMISSION_ADD_COMMENTS_TO_CLOSED_DISCUSSION\";N;s:25:\"PERMISSION_ADD_CATEGORIES\";N;s:26:\"PERMISSION_EDIT_CATEGORIES\";N;s:28:\"PERMISSION_REMOVE_CATEGORIES\";N;s:26:\"PERMISSION_SORT_CATEGORIES\";N;s:28:\"PERMISSION_VIEW_ALL_WHISPERS\";N;s:29:\"PERMISSION_APPROVE_APPLICANTS\";N;s:27:\"PERMISSION_CHANGE_USER_ROLE\";N;s:21:\"PERMISSION_EDIT_USERS\";N;s:31:\"PERMISSION_IP_ADDRESSES_VISIBLE\";N;s:30:\"PERMISSION_MANAGE_REGISTRATION\";N;s:21:\"PERMISSION_SORT_ROLES\";N;s:20:\"PERMISSION_ADD_ROLES\";N;s:21:\"PERMISSION_EDIT_ROLES\";N;s:23:\"PERMISSION_REMOVE_ROLES\";N;s:28:\"PERMISSION_CHECK_FOR_UPDATES\";N;s:38:\"PERMISSION_CHANGE_APPLICATION_SETTINGS\";N;s:28:\"PERMISSION_MANAGE_EXTENSIONS\";N;s:26:\"PERMISSION_MANAGE_LANGUAGE\";N;s:24:\"PERMISSION_MANAGE_STYLES\";N;s:27:\"PERMISSION_ALLOW_DEBUG_INFO\";N;s:27:\"PERMISSION_DATABASE_CLEANUP\";N;}',1,'0'),
('Member','1','1','1','0','a:33:{s:23:\"PERMISSION_ADD_COMMENTS\";i:1;s:27:\"PERMISSION_START_DISCUSSION\";i:1;s:27:\"PERMISSION_SINK_DISCUSSIONS\";i:1;s:28:\"PERMISSION_STICK_DISCUSSIONS\";N;s:27:\"PERMISSION_HIDE_DISCUSSIONS\";N;s:28:\"PERMISSION_CLOSE_DISCUSSIONS\";N;s:27:\"PERMISSION_EDIT_DISCUSSIONS\";N;s:34:\"PERMISSION_VIEW_HIDDEN_DISCUSSIONS\";N;s:24:\"PERMISSION_EDIT_COMMENTS\";N;s:24:\"PERMISSION_HIDE_COMMENTS\";N;s:31:\"PERMISSION_VIEW_HIDDEN_COMMENTS\";N;s:44:\"PERMISSION_ADD_COMMENTS_TO_CLOSED_DISCUSSION\";N;s:25:\"PERMISSION_ADD_CATEGORIES\";N;s:26:\"PERMISSION_EDIT_CATEGORIES\";N;s:28:\"PERMISSION_REMOVE_CATEGORIES\";N;s:26:\"PERMISSION_SORT_CATEGORIES\";N;s:28:\"PERMISSION_VIEW_ALL_WHISPERS\";N;s:29:\"PERMISSION_APPROVE_APPLICANTS\";N;s:27:\"PERMISSION_CHANGE_USER_ROLE\";N;s:21:\"PERMISSION_EDIT_USERS\";N;s:31:\"PERMISSION_IP_ADDRESSES_VISIBLE\";N;s:30:\"PERMISSION_MANAGE_REGISTRATION\";N;s:21:\"PERMISSION_SORT_ROLES\";N;s:20:\"PERMISSION_ADD_ROLES\";N;s:21:\"PERMISSION_EDIT_ROLES\";N;s:23:\"PERMISSION_REMOVE_ROLES\";N;s:28:\"PERMISSION_CHECK_FOR_UPDATES\";N;s:38:\"PERMISSION_CHANGE_APPLICATION_SETTINGS\";N;s:28:\"PERMISSION_MANAGE_EXTENSIONS\";N;s:26:\"PERMISSION_MANAGE_LANGUAGE\";N;s:24:\"PERMISSION_MANAGE_STYLES\";N;s:27:\"PERMISSION_ALLOW_DEBUG_INFO\";N;s:27:\"PERMISSION_DATABASE_CLEANUP\";N;}',2,'0'),
('Administrator','1','1','1','1','a:34:{s:23:\"PERMISSION_ADD_COMMENTS\";i:1;s:27:\"PERMISSION_START_DISCUSSION\";i:1;s:27:\"PERMISSION_SINK_DISCUSSIONS\";i:1;s:28:\"PERMISSION_STICK_DISCUSSIONS\";i:1;s:27:\"PERMISSION_HIDE_DISCUSSIONS\";i:1;s:28:\"PERMISSION_CLOSE_DISCUSSIONS\";i:1;s:27:\"PERMISSION_EDIT_DISCUSSIONS\";i:1;s:34:\"PERMISSION_VIEW_HIDDEN_DISCUSSIONS\";i:1;s:24:\"PERMISSION_EDIT_COMMENTS\";i:1;s:24:\"PERMISSION_HIDE_COMMENTS\";i:1;s:31:\"PERMISSION_VIEW_HIDDEN_COMMENTS\";i:1;s:44:\"PERMISSION_ADD_COMMENTS_TO_CLOSED_DISCUSSION\";i:1;s:25:\"PERMISSION_ADD_CATEGORIES\";i:1;s:26:\"PERMISSION_EDIT_CATEGORIES\";i:1;s:28:\"PERMISSION_REMOVE_CATEGORIES\";i:1;s:26:\"PERMISSION_SORT_CATEGORIES\";i:1;s:28:\"PERMISSION_VIEW_ALL_WHISPERS\";i:1;s:29:\"PERMISSION_APPROVE_APPLICANTS\";i:1;s:27:\"PERMISSION_CHANGE_USER_ROLE\";i:1;s:21:\"PERMISSION_EDIT_USERS\";i:1;s:31:\"PERMISSION_IP_ADDRESSES_VISIBLE\";i:1;s:30:\"PERMISSION_MANAGE_REGISTRATION\";i:1;s:21:\"PERMISSION_SORT_ROLES\";i:1;s:20:\"PERMISSION_ADD_ROLES\";i:1;s:21:\"PERMISSION_EDIT_ROLES\";i:1;s:23:\"PERMISSION_REMOVE_ROLES\";i:1;s:28:\"PERMISSION_CHECK_FOR_UPDATES\";i:1;s:38:\"PERMISSION_CHANGE_APPLICATION_SETTINGS\";i:1;s:28:\"PERMISSION_MANAGE_EXTENSIONS\";i:1;s:26:\"PERMISSION_MANAGE_LANGUAGE\";i:1;s:24:\"PERMISSION_MANAGE_THEMES\";i:1;s:24:\"PERMISSION_MANAGE_STYLES\";i:1;s:27:\"PERMISSION_ALLOW_DEBUG_INFO\";i:1;s:27:\"PERMISSION_DATABASE_CLEANUP\";i:1;}',4,'0');
</code>
Will restore all roles back to default but you'll need to truncate the table first. Looks to me like there isnt an applicant role as standard though? I'm pretty sure applicant is a pseudo-role.