Delete all local changesets and revert to tree

When the simplest way (a new hg clone) isn't practical, I use hg strip:

% hg outgoing -l 1
% hg strip $rev # replace $rev with the revision number from outgoing

Repeat until hg outgoing stays quiet. Note that hg strip $rev obliterates $rev and all its descendants.

Note that you may have to first enable strip in your Mercurial settings.

PS: an even smarter approach is to use the revset language, and do:

% hg strip 'roots(outgoing())'

You'll want to make a local clone where you preserve only the changesets that are also present in the remote repository. Use TortoiseHg, hg log or similar to figure out which of your revisions is that lastest revision you didn't make (the one before the mess started). Using hg outgoing can help here -- it will list all the changesets you made -- pick a revision number earlier than any of those.

If the target revision is called good and your clone is called foo, then do:

hg clone -r good foo foo-clean

This will be a fast, local operation -- there is no reason to download everything again. The foo-clean clone will only contain changesets up to revision good. You can now replace foo-clean/.hg/hgrc with foo/.hg/hgrc in order to preserve your repository-local settings such as the default push/pull path.

When you are satisfied that foo-clean has everything you need from foo, then simply delete foo and rename foo-clean to foo. Do a hg pull to get any new changesets from the remote repository into your clone and continue like normal.

If nobody has pushed new changesets to the remote repository, then it is very simple to determine which revision you want to use as good above: hg id default will tell you the ID of the tip in the remote repository.

Ok. So just delete all the local stuff, hg init the new local repository and hg pull the latest tip you have. Don't forget to hg update after this.