After seeing the following from the command line:
# On branch RB_3.0.10
# Changed but not updated:
# (use \"git add ...\" to update what will b
It might be line endings, as @1800-information suggests, but another possibility is that the difference (that's preventing your from reverting these files with a checkout command) is one of file mode. This is what happened to me. On my version of git you can discover this by using
git diff index.htm
And it will show you file mode changes. It still won't let you revert them, though, using checkout, even with the -f option. For that use either
git config core.filemode false
or change your git .config in your text editor by adding
[core]
filemode = false
After you do this, you can use
git reset HEAD index.htm
and the file should disappear.
(I got all of this from the answers to How do I make git ignore mode changes (chmod)? and updating-file-permissions-only-in-git)