In my experience - with the same issue, i.e. power cut - you can attempt to copy and paste things from other "whole" projects because maybe one or more might be corrupt, not all of them, but in the end it's better to start again. With MV in particular you have the advantage of separate plugin "scripts", which can more easily be ported back into your game. With the other RPG Makers, once the script data was corrupted that's it, non-recoverable; you have to start ALL over again. Most important of all (learned the hard way) back up your entire project regularly so you can copy and past your "good" project back into its current folder!