If it's any consolation i've just had a similar thing happen. Went to add a playlist and it wiped 35 gig of music off my iPod touch 64g in a nanosecond. I've got the latest iTunes and osx but do not back up because i keep different styles of music (and loads of it) in separate libraries and devices which i don't want mixed together. All my stuff is burned from cd so it's not lost for good and i've got a hard drive with the "lost" mp3 music on it but even so it will take literally weeks to prune the tracks for my iPod to be the same again. Why do they make it so difficult to manage your music on these things. I have massive amounts of music on my computer so autofill is a disastrous unusable gimmick to me. The whole thing seems to be aimed at 9 year old kids with about 6 mp3's on their phone rather than serious music lovers (for example accessing EQ is a joke let alone the lack of a manual option). I'm a dj and use apple for that reason but to be honest i'm beginning to wonder why. I'm absolutely livid. The weird thing is that my mac still shows the titles of the missing tunes in the 'on my device' window but as my macbook storage display shows no increase i'm pretty sure it's all gone. Nightmare. I have no confidence in this device anymore and could barely use the previous osx 8.2 anyway. Why they have to change it every ten minutes is beyond me. As the old saying goes 'if it ain't broke, don't fix it' but this format just gets more broken every time they update. An absolute disgrace. Why not just drag and drop or delete. No wonder the iPod is said to be a dying device, it's for music, it is not a phone. Not fit for purpose anymore. I can't be bothered to read a massive 'how to use' article every update. Good technology should be easier and more intuitive with each new version. I suppose i'll have to phone apple at my expense to find out what's going on, or maybe that's the whole idea. Very very very not happy.
