Well, the Warning seems clear enough to me.
As for the white screen, I imagine settings are a crucial part of Drupal being able to work, and since that file has a problem Drupal can not proceed any further.
As indicated in the Warning message, the drupal/sites/default/settings.php file.
Unterminated comment starting line 238
If you didn’t edit that file, I imagine it is less likely to be a Drupal error but more likely to be a corrupt file.
eg. there was an interruption during FTP upload / installation and the file wasn’t written completely.