OK, I tried to go back to 10.7 using the following methods gleaned from here and other threads:
1. Using terminal cd /Applications then sudo rm -R iTunes.app to delete iTunes
2. Restore the old library iTunes.itl from a CrashPlan backup before updating to 11. Same thing for iTunes Library Extras.itdb which seems to have been modified by iTunes 11.
3. Open the 10.7 installer .pkg file in Pacifist.
4. Install. When it asked to replace I said yes and turned off the confirmation for each one. When it gave the choice of updating or replacing then one time I tried replacing and one time I tried updating. In both cases, when I tried to launch iTunes it complained that it could not launch because there was a newer library file.
The message is "The file "iTunes Library.itl cannot be read because it was created by a newer version of iTunes. Would you like to download iTunes now?"
But I restored this file! Can anyone help?