apparently the board was originally installed using the host's one click install script. they often have an auto upgrade script that runs without your knowledge. this is very dangerous if you have added any MODs/ extensions /styles etc.
often we see where the auto upgrade just wipes everything out and starts over. that may be why it is not finding whatever styles those two are.
they are not standard phpbb styles available here.
the auto updater has apparently removed those two styles from the styles folder. now you get errors.
the first thing I would do is make a complete database backup using phpmyadmin or whatever your host provides for that.
be sure it is complete and safe on your computer before you start any actions below.
if you know where those styles came from and/or if you have a backup copy of them then reupload them to the styles folder and those errors will go away.
if not, then you will need to access the database directly to deactivate them and/or remove them.
you MUST be careful if you decide to edit the database as you can really mess it up if you don't know what you are doing.
I am available for custom work on a donation basis. Please send me a PM with your needs.
Premium phpBB 3.2 Styles
OK, so what's the speed of dark?