How to recover from a failed update/merge?

I have this multi-platform app in SVN thet I started in Windows but
lately have worked on in Linux.
The correct latest version is from Linux and I wanted to verify it on
Windows.

Everything is committed from Linux and the revision there is the
current one.

Now I made a mistake in Windows and don't know how to get out of it...
I had started the IDE and when checking the code I realized it was not
current, but the fact that I checked modified local files.

Next mistake, I went to the command line and did an svn up to get the
latest versions forgetting the IDE was still running, so it now
intervened and tried to be clever about the changing files.

Meanwhile svn started to offer some merge suggestions which I had
never done before and after a while I had this mess....

So now I need to get a clean slate on the source dir in Windows, i.e I
want to get the *repository revision* of all files in the source dir
and not bother with bogus changes made in the messup.

How should I proceed to get the wc in a state like after the last
successful update so it can now be updated to the repository head
revision?

-- 
Bo Berglund
Developer in Sweden