Those of you who worked or used in the past the ~/Library user Library directory will notice that Apple has hidden this directory. This is probably to keep people from accidentally deleting or damaging files that are necessary for OS X Lion to function properly.
There is one simple terminal command to make this directory visible again.
Launch Terminal from the Utilities Folder or type Terminal in your Spotlight search.
Enter the following command in the Terminal.app to hide or show the directory:
sudo chflags nohidden ~/Library/
The users Library folder will immediately become visible again. If you want to set it back to invisible type
sudo chflags hidden ~/Library/