The current Blogger drama: conclusion
Okay, the problem was that Blogger arbitrarily deleted my main template, so obviously it was having some transfer errors. Unfortunately I never foresaw such a problem so I had no backup of my template. So I was pretty much fucked, right? No. Here's how I fixed it:

I loaded this weblog in another tab (it looked the same as before because it wasn't being published since the template disappearance). I "viewed source", copied and pasted the entire HTML code of the page into the template window of Blogger. Then I put my nose to the grindstone and converted it from raw HTML into a useable template again.

And now I have, and will always have, a backup copy.

Note: My archive template is fucked because the only way I could get Blogger to notice me changing my template was to go to "choose template" and load one of their premade ones. Then saved and published. Then deleted the new Blogger template and copied/pasted my own (from my backup copy) into the window. And viola, I tricked Blogger once again. But little did I know, that "chosen" template also changed the archive template, which was otherwise fine, so I'll have to redo it from scratch. Anyway, that will happen later. I need to get away from this screen.

Edit: Archive is fixed. Archive is backed up. Let's just pretend the whole thing never happened, shall we?