Okay, go into the save file folder for Pokemon reborn. There will an item called "Game", this is the file that the game reads whenever it goes to load up a save. If you have backups there will be other files in there as well. These will have your character's name, badge number, playtime, etc. If one of these matches your old character than all you have to do is rename that file "Game" and you can continue playing the old one. Note that there are a limited number of backups, so if you want two different save files you will need to store your other game's file in another location so it can't be automatically deleted when you hit the max number of backups.
And what do you mean that your rejuvenation file refuses to be recognized?