debug a Forum website code

There is a link to the Forum from the website. I recently created forums on the website but for some reasons it started giving the following errors messages: I must have accidentally deleted something on the front end. phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 432: Invalid argument supplied for foreach() [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 432: Invalid argument supplied for foreach() [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 432: Invalid argument supplied for foreach() [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 1007: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 1007: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 1007: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /[login to view URL] on line 36: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 4184: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 4186: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 4187: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL]) [phpBB Debug] PHP Notice: in file /includes/[login to view URL] on line 4188: Cannot modify header information - headers already sent by (output started at /includes/[login to view URL])