Subversion retains history, so if you check in deletions, your data is not deleted. For example, if you had a directory /my/directory and deleted it in revision 2450, you could do the following to bring it back:

svn copy -r 2449 

You can also use Subversion merge to merge changes in from a previous revision, but bear in mind that merge will pull in all changes from the previous revision, so the copy is a more targeted way to fix the problem.