How to load a previous save in Minecraft?

So, I was in Hexxit (a modpack) and I saw capsules. There was also a capsule station or something, so I figured it was a workbench. I took the big one and placed it down, right in the middle of my house, and next to all my chests. I clicked and it cleared a 10x10 - ish radius of blocks. The house was inside an overhang too, so it looked natural and that's what my house was, so I can't replace that or any of my items. Please help, my friend will be furious with me if in about a week he logs in to find there's a huge hole where our base used to be!

If you are playing on a private server you can try to reload a back-up the server made (that only works if the server is able to do that). If that doesn't work you're screwed.