Ok I tried again.

I replaced the 5 files from your download then edited the functions.inc from this:

function getAvatar($user_id) {
 $avatar_images_path = 'images/avatars/';
 $fileIterator = new FilesystemIterator($avatar_images_path);
 $regexFileFilterIterator = new RegexIterator($fileIterator, "/\D+(".preg_quote(intval($user_id), '/')."(_\d+)?\.(jpg|gif|png|jpeg)$)/i", RegexIterator::GET_MATCH);
 $regexFileFilterIterator->rewind();
 $filename = ($regexFileFilterIterator->valid() && count($regexFileFilterIterator->current()) > 1) ? $regexFileFilterIterator->current()[1] : false;
 if ($filename === false || !file_exists($avatar_images_path.$filename))
  return false;
 return array($avatar_images_path, $filename, $avatar_images_path.$filename);
}

to this

function getAvatar($user_id) {
 $avatar_images_path = 'images/avatars/';
 $fileList = glob( $avatar_images_path . intval($user_id) . "[_.]*{png,jpg,jpeg,gif,bmp}" , GLOB_BRACE);
 if (isset($fileList) && count($fileList) > 0) {
  foreach ($fileList as $file) {
   if (preg_match("/^(" . preg_quote($avatar_images_path, '/') . ")(" . preg_quote(intval($user_id)) . "(_\d+)?\.(jpg|gif|png|jpeg,bmp))$/", $file, $matches)) {
    //var_dump($matches);
    $filename = $matches[2];
    if (file_exists($avatar_images_path.$filename))
     return array($avatar_images_path, $filename, $avatar_images_path.$filename);
   }
  }
 }
 return false;
}

and it seems to be working now. I have not tried

Now, please add a sample output. Please edit the avatar.inc.php. Look for:

Do I need to do this?
Thanks