I have deleted by mistake an entire package in eclipse.
I tried to search in the local history as written in the :
"Restoring deleted resources from local history"
, but it is still writing that the folders don't exist !!
I have searched also in the folders of the whole project in the bin & src.
That's where Version control comes to picture.
In case if you've checked "Delete contents on disk" checkbox while you accidentally deleted the package, then I am pretty sure you'll not be able to recover it.
The situation is quite unfortunate. This can be prevented in the future by a VCS.