during the backup process, there's a backup file created which stores all your bb data. the file usually looks something like "backup-(mm-dd-yyyy)" and it defaults to the "my documents" folder. since you didn't perform a manual backup prior to the upgrade, i highly doubt dm saved the backup file there.
(this is me assuming here) dm likely creates a temp file somewhere and dumps it once the process completes. i'm not really sure if there would be a temp file backup somewhere on the computer, but it wouldn't hurt to look for one.
