Since this game is really that great, in my eyes it's most simple to start a brand new game.
Okay, it's sadly your xbox profile got corrupted, but I ask myself: "How can that been happen?" Corrupted? Strange !
Try first to make a second profile and try if you can set that new profile as your default one so you can play further on with all your saved game slots. If that not work, try to contact Microsoft service and see how that work ?
Otherwise I think you can give some more info about your Xbox version (in which country do you live? - because there's a difference between the Xbox (& games)in Europe and out of Europe !
I live in Europe and for example someone in America CAN'T do anything with my Xbox savegames !
PLUS : have you the very first version (Ego Draconis) or the remastered version DKS => The Dragon Knight Saga (= Ego Draconsi + Flames of Vengeance, together on 1 disc for your Xbox)
Somewhere on this forum someone of the devs of Larian give info about "How to send a Xbox savegame via a computer" ... (that was needed for helping people with a bug in their Xbox savegame)
Via that way, maybe someone can help you to send you a savegame.
I don't know how far you was in DKS? I've a savegame at L19, so that's good if you wish to go fast to the Battle Tower and kill Laiken
Hope you can solve all your problems soon and join us on this forum and have fun with the DKS !