Microsoft changed directory setting

I have thousands of images on a backup directory which was known as F. But a recent Microsoft update has now changed the backup directory name to H and, of course, Lightroom is now showing all of those previously referenced folders on F: directory with ?.  How on earth do I get this sorted? It will mean I need to either name the referenced directory as H - if there's a way to do that, or somehow tell Lightroom that the folder is now elsewhere, which is isn't really, it's just got a new name.

What do I do please?