This is the second time this has happened to me, and the first time I chalked it up to some "user error". It happened again so I will post in here for any ideas / thoughts.
Here is a picture of the installed software I have.
I have no option to create a web application project, I can't show the Development Mode View, doesn't recognize GAE or GWT library folders, JSNI methods don't have auto-complete, etc.
The only thing that appears to be working, is the "Google" properties inside the project, I can edit those.
Everything appears to be installed, is there something I am missing?, or any way that I can see why some stuff is missing?
I have found 2 good methods to handle Eclipse breaking.
Start from Scratch
a. Download or Locate an Eclipse Archive and place the contents in a new folder.
b. Launch the New install.
c. Perform Updates.
d. Re-install all necessary addons.
Rollback your install/updates to a working version.
a. Select the Help Menu
b. Select About Eclipse (Usually at the Bottom)
c. Click the "Installation Details" Button (Lower Left Hand Corner)
d. Select the 2nd Tab "Installation History"
e. Select one of the Available options
f. Follow the wizard instruction to "Revert"
Neither of these options have ever failed in getting me back to work. They are not the most expedient, but they work every time.