I’ve had a problem for a couple of days now where Eclipse would not load in my main workspace. I had a couple of other workspaces to test, and they worked fine. After many failed suggestion, I finally found one that worked.
Go to your workspace folder, and descend into the .metadata/.plugins folder. Once you are there, delete the entire tree for org.eclipse.core.resources.
Start up Eclipse, select the same workspace folder, and Eclipse should start up. Just import all of your existing Eclipse projects, and you should be all set!
Special thanks to the author of the following page for pointing me in the right direction:
http://letsgetdugg.com/2009/04/19/recovering-a-corrupt-eclipse-workspace/
