do an Erase and Install.
This will put your machine back to the same state that it was in when you first opened the box.
Beware, ALL the data on your hard drive will be erased!
Are you an Apple Developer?
Here's what happened: I installed the OSX Lion Developer seed. I found it to have too many bugs so I reinstalled Snow Leopard from the original DVD. Now I cannot get the following to start: IPhoto, APerture, JDownloader. On the other IGetter downloads "break". My Airport does not connect automatically, etc.
I found that I am missing my user Library Folder. It is not in the Home folder and when I do a Spotlight search nothing shows up.
I know I did a stupid thing installing beta software as an update and not on a different partition.
Does anyone have any ideas on how to get my MacBook Pro back on its feet?