Assuming the hash of the commit you want is
git checkout c5f567 -- file1/to/restore file2/to/restore
The git checkout man page gives more information.
If you want to revert to the commit before
~1 (where 1 is the number of commits you want to go back, it can be anything):
git checkout c5f567~1 -- file1/to/restore file2/to/restore
As a side note, I've always been uncomfortable with this command because it's used for both ordinary things (changing between branches) and unusual, destructive things (discarding changes in the working directory).