after you switch back to single player move your folders back from appdata. And make zip/7z backup in TT folder, so you can backup your snapshots and savegames from there and not from appdata, if this happen again.
OK... i will never give advises for Mac again. Usually if we make backup on windows that means we made zip or 7z archive and if you know how to make it you will know how to open it and use it (usually)
Is this backup of whole hard disc? If it is recent it should be possible to extract your folders but I have no idea what software you should use.