Error in Script with PHP 7.1 [closed]

I have a problem with a module that used to work correctly in PHP version 5.6.

After upgrading PHP from server to 7.1 it crashed due to some functions that were previously present in PHP 5.6 and no longer exist from version 7.1.

When I try to run the module, it returns the following error:

Erro no Comando do Módulo
mysql_data_seek is not supported

Here is a snippet of code with the function mysql_data_seek , where the error occurs:

  function _mysql_result($result, $iRow, $field = 0)
{
    if(!mysql_data_seek($result, $iRow))
        return false;
    if(!($row = mysql_fetch_array($result)))
        return false;
    if(!array_key_exists($field, $row))
        return false;
    return $row[$field];
}

According to PHP I need to change to MySQLi, but my knowledge is very limited on this issue.

If anyone can give me a light.