I put my Nether Reactor near my house then activated it. My whole house turned to obsidian and all my chests were destroyed and I lost most of the items inside because I couldn't carry it all. Is there some way to deactivate it and get my house back?
The Nether Reactor will burn out 45 seconds after it is activated, so that's a problem that will take care of itself rather promptly. However, it is impossible to retrive the items that were destroyed, including your chests. Remember, kids: nether reactors aren't toys, don't try this at home!