Let me preface this by saying that I am completely new to all this and am working off of a website that someone else set up, etc etc. If you know what I need to do to fix these issues, please be clear and detailed - assume I don't know anything except how to log in to WordPress!
Now, I'm not sure where the problem is, but I can explain what's happened so far. I tried to backup our site, using the WordPress Backup to Dropbox plugin, and kept getting this error:
"...Exception - RecursiveDirectoryIterator::__construct(/home/****/public_html/wp-content/themes/twentyten/log) [recursivedirectoryiterator.--construct]: failed to open dir: Permission denied"
I don't know what that's about, but we don't use the TwentyTen theme. If I had to revert to a default, I'm assuming it would be the newer TwentyEleven. Since there's an option to delete both of those themes through WordPress, I clicked to delete TwentyTen. That didn't fix the backup error, and it started showing TwentyTen as a broken theme under "Manage Themes," with "Stylesheet is missing" as the description. I had downloaded the TwentyTen theme to try to reinstall it, but first I tried adding the stylesheet file through my FTP file manager, and that took it out of broken themes. I couldn't figure out how to re-install it at that point, so I moved on to try something else.
Both TwentyTen and TwentyEleven had been showing they had available updates, so I decided to update TwentyEleven. When I did so, it told me the update failed. Now TwentyEleven only shows as a broken theme, again with "Stylesheet is missing," and when I look at the files in my Themes folder in the FTP stuff, the folders are there but all the files seem to be missing if that makes sense. It looks different than what's in the TwentyTen .zip file, whereas before I tried to update it looked very similar.
So the last thing I tried was to reinstall the TwentyTen theme by uploading the .zip file I had, and that also failed. It says:
"Destination folder already exists. /home/*****/public_html/wp-content/themes/twentyten/
Theme install failed."
I've tried to delete the twentyten folder from my file manager, but it just keeps showing up.
What on earth is going on here, and how can I fix it?