Unfortunately you can't. If you try to open .html files in publisher you just get the html source code. You could, however, open them in Frontpage (if you have it that is).
Sounds like you learned the lesson the hard way :o)
When you send your files to your webspace why not send .pub files as well. This will act as backup and ensure that what is there is the latest 'live' version (providing you have enough space).
We live and learn!