Home Page Options, Pages, Posts All Missing. Other Settings Changed

Site: https://creativestudent.radism.net/

I have been using WordPress software for more than six months. Everything has been going fine, and was fine when i check a couple of hours ago. All I did was a brief edit to a post (deleted a few words that I’d forgot to delete before publishing the post). Nothing unusual. I also updated WordPress’s Jetpack plug-in not long before this, but everything was fine after the update.

I then added some SEO things to the post – the meta-title and the description of the post that comes up on search engines. When I tried to save the changes, I got a “Are you sure you want to do this” message, so I cancelled the action.

I then noticed my home page was missing (when I visited the page, I got a “page not found” error.) and so was my navigation bar. (The bar itself was there, but was blank.) The navigation bar has done this before, but last time it was simply a font error – the links had still been there and simply changing the font size had fixed it.

I went to check the home page settings, but those were missing from the “Reading” page. The only options on that page are now:
-Blog pages show at most ____ posts
-Syndication feeds show the most recent ___ items
-For each article in a feed, show: full text or summary
Encoding for pages and feeds _____

The options for having either a static home page, or feed are no longer there.

I when to “pages” to see if there was something wrong there. All pages were gone. Previously there had been multiple pages, a draft, active pages, and some in the trash folder. All were gone, and there was nothing about a trash folder existing. When the pages in the trash folder were moved there, (at least several days ago) I triple checked everything and double checked afterwards to make sure I hadn’t deleted the wrong thing.

I then decided to search my site for the posts, and it came up saying that nothing could be found. I checked “posts” and there was nothing there. There is nothing in a “trash” folder or anything, its just blank.

I have a 404 page error notifier, which is now saying that every page and post is coming up with this error.

I have not deleted any files, or made any system changes. There are no new plug-ins or anything else.

And just in case it is important:

I use the Pilcrow 1.2 theme.
The list of active plug-ins installed are:
AddThis Social Bookmarking Widget
Akismet
Broken Link Checker
CommentLuv
Comment Reply Notification
Defensio Anti-Spam
Feedburner FeedSmith
Google Analyticator
Google XML Sitemaps
Jetpack by WordPress.com
Network Publisher
NoFollow Free
Redirection
Search Everything
SEO Helper
SEO Ultimate
Share and Follow
Social Homes
Subscribe 2
W3 Total Cache
Wapple Architect
Wordpress Importer
WP-Cufon
WP-DBManager
WP-Typography
WP Super Cache
Yet Another Related Posts Plugin

None of these are new, and none have caused any problems in the past.

Any help would be most appreciated. I write all my posts on my computer so I still have copies (I’m very glad of that), but it has still caused quite a disruption – comments still seem to exist, but wont be attached to the posts if i reload them, I’ll have to rewrite my about page and disclaimer, and simply reinserting all the images will take ages, as they all have to be resized properly, and everything else (they are not uploaded to the same website). If nothing else, it would be nice to understand what happened and/or how.

Thank you.