Update deleted all previous music, can't find Previous iTunes Library

So, the recent update completely destroyed all my playlists and album art and well... everything. Following the scattered advice on forums and elsewhere, I keep being told to restore my library from Previous iTunes Library folder.

But, it simply isn't there. I'm looking in the correct place, I'm in the iTunes folder in My Music, I can see all the other files I need to see but the file I need simply doesn't exist!

I tried the trick where you delete the relevant file in the iTunes folder, after moving the other into a desktop file. However, when it recreated the library, it instantly deleted the file I'd moved over into desktop, and now there is no music, no TV, not a single scrap of my library remains.

And, to top it all off, a separate problem, my recycling bin has become corrupted and I can't bring back deleted files. At all.

So, I want to backup from the Previous iTunes Library folder, but I simply CAN'T. Can anyone help?

ALSO, I have found a seeming correct backup buried deep in appdaata/roaming etc etc, and it's date corresponds to when I updated iTunes, so that should be fine. But, I can't backup from it! It simply won't let me. I can see a whole bunch of weird files with lots of different letters and numbers and nothing else. IK can't backup from any of these files, even though I KNOW that they're the backup.

Is there anyway I can force this **** program to backup?