As luck (of the Irish) would have it, right after I took a complete backup of the site, I decided to change something which hosed all of the images on the site (or at least, confused the database about the location of the various sizes of each image). I wanted to change the thumbnail size from 150 to 130 so that more images will fit per gallery, but changing that setting caused a massive problem somehow.

I managed to upload the saved copy of the database with no problem, and uploaded all the images again (in the files/images directory), though I don't know if that was necessary, and got the site up and running again. Just as it came up live, they took the server down for an upgrade! which was very disconcerting since I thought it was my problem, not a server maintenance issue. Luckily I found a post on the server's announcement board pretty soon after the issue occurred. I don't know what really happened, since I'm still unfamiliar with the how the database really works :p

It's a priority to me to figure out what the proper procedure for changing the image thumbnail size would be as well as the correct method to recover from such a disaster. My solution wouldn't work very well if I didn't have a recent backup of the database... All the posts made since the database backup would be gone! So I need to know how the image resizing and linking is working behind the scenes.