Searching all git objects

Hi all,

We recently had a developer make a large commit (mostly centered around one file) which she believed she properly pushed to a remote repository last week, but looking at both her repository and the remote repository, that commit is now nowhere to be found. If somehow the master branch she was working on in her repository has lost the reference to the commit through perhaps some errant rebasing, then perhaps an object containing the commit (or an object containing the file in that commit) still exists somewhere inside her .git/objects directory? We haven't done any git-gc recently. If so, how can I search through every single git object in her objects directory, searching for perhaps a specific part of the commit string, a line in the code or the filename of the file which was changed? Any help with this would be greatly appreciated. Thanks!

-Sam