Hi,

LCK file is created when the page is being edited. This LCK file is used to
lock the file so that only one instance can edit the page in one time. Now that
you are not able to edit the index page and that a lck file has been created,
it implies that the page is being edited by someone else. In order to make the
page editable, Could you please remove the lck file say index.html.lck file.
Any changes the other user had made will be discarded and the vpublished
version of the page will be available as latest.

Hope this helps.

Thanks.