go to C:\users\username\saved games\pokemon reborn where you will find your save file and backup save files - make sure to transfer Game.rxdata and some of the backups (they are named something like number-ID-badges)
and transfer those to your new pc in the same location, if you don't have that folder on your new pc then start a new game on new pc and save when you have first chance to create the folder. When transferring your old save make sure to replace the new save you've made to create the folder
your save file got corrupted, to fix this use your back up save files -> you should have save backups in here (they are named number - Player name - badges) C:\users\username\saved games\pokemon rejuvenation to make them work just rename one of the file to Game.rxdata
sometimes you have to use multiple backups to make it work
Question for people who have sun/moon. I'm planning on making breedject giveaways and I've already breed some of the mons (mareanie,vulpix,sandshrew,grimer,cubone,mimikyu,minior) but I'd like to hear what else would you like to see in them