I had the same problem when i went to 4.2 The files are there but im pretty sure you can find them and relocate them using a file manager but im not 100%
Use file explorer look under /sdcard/0 it should be in there
When I did my ROM Manager upgrade to the latest nightly (2012-12-24), I got "Upgrading Media Database", and I realized my 20 gigabytes of media was going to take longer than most people, so I looked on the web to see if this was a time issue. Apparently, it's not just a time issue, but a MASSIVE one, and I estimated I'd have to wait about a week for mine to complete. Well, guess what, I actually USE my smartphone, so this was unacceptable, so I battery-pulled. I rebooted several times to find the device unusable due to it being so slow it basically crashes after a few minutes or less,
so I decided to Clockworkmod Nandroid Restore, and got "no files found" when trying to do that. I then again looked here and found out that the files normally in /data/media/clockworkmod are now in /data/media/0/clockworkmod, so
I installed an older adb from
http://forum.xda-developers.com/showthread.php?t=1387527 on my older MacOS 10.5.8 to access my ClockworkMod Recovery v6.0.2.3 shell (the current Google.Com adb doesn't work with MacOS older than 10.6 any more).
Then, from adb shell, I did "cd /data/media; ln -s 0/clockworkmod .", then suddenly all the files were found, and the Nandroid Restore proceeded.
I just rebooted right now, and SO FAR everything looks OK (back to my old ROM as Nandroid Restored):
+ Camera works
+ SMSs work
+ Wifi works
+ GPS works
+ Social app using Wifi & GPS works fine
So, I'm back in business. Thank god for Nandroid Restore! I'll let some of the experience level of upgrading settle down on this one! And let some of the bugs work out too ...
STOP THE PRESSES! Gallery is messed up. Ohkay ..... it seems like Gallery always gets messed up.
Ohhhhh ... /sdcard/ isn't what it seems. /sdcard/* was moved to /sdcard/0/*, so I have to move it back. One moment while I do that (in recovery) ...
So, there was quite a bit of new directories in /sdcard/* pretty empty to replace the missing ones hiding in /sdcard/0, so I had to sort of move them out of the way (trash, rename, etc.), then move /sdcard/0/* and /sdcard/0/.??* back to /sdcard/.
Gallery does not start properly, but I force stopped it, cleared data (in manage apps), and now it starts properly.
My phone is back to normal, as far as I can tell.