I just downloaded Unity 3.5 and all my assets in my unity Project is gone (all meshs gone). I am very angry and worked on my game for over 2 Years!! Tell Me How To Fix It!!
-Kickasskane Productions.
Hopefully you have backups of your work.
I saw meshes go bad on 3.5 Beta and sent a bug report about it. They did not fix it in the 3.5 final (I hope they get around to it in a point release). Please report the bug via Unity and sent email too to support.unity3d.com.
In the mean time, you should still have your 3.4 handy right? Reinstall that, and go back to using that. If your project (scenes) won’t load (and you have no backups), you may need to recreate some things from memory, but at least your meshes should be intact.