My recent migration to Subversion caused me to loose recent updates from a project in my workspace. I'd broken the workspace by checking subversion files out to the wrong level and then deleting madly. Unfortunately when I restored the project from backup some recent updates were missing and there was no Eclipse history available for the files in that project
After some searching I found that Eclipse stores all its history data in
workspace/.metadata/.plugins/org.eclipse.core.resources/.historybut using "search in file" on XP didn't find my files. I did have cygwin installed so I used
find . -type f | xargs grep someUniqueString -to locate the file successfully. So now I know how to cope with a small case of Eclipse amnesia.