You could try OWL. Just move to the location you want to check and click on “History (beta)”. The red lines are deleted ways. Is it this one you’re looking for?
Btw: We sometimes have the same problems in germany, but I think it is good to have those images.
Please have first a look at http://wiki.openstreetmap.org/wiki/Change_monitoring#Monitoring_Tools … thus you can find: who edited what, and when.
So I was able (via http://owl.apis.dev.openstreetmap.org ) to reveal this changeset: http://owl.apis.dev.openstreetmap.org
try to contact that mapper and ask hin why he deleted that way.
If you want do do some undeleting, see http://wiki.openstreetmap.org/wiki/Change_rollback
Are you sure the roads s/he added in the changeset are wrong, too? If not, I might have been more appropriate to undo the changeset only partly imho.
With the Reverter-Plugin for JOSM. Use [Ctrl]+[Shift]+[T] to open it’s dialouge. To only restore deleted Objects select an object which is not in the changeset (i.e. on the other side of the world) before opening the dialouge and choose something like “Revert Selection and restore deleted Objects” (I’m using a non-english loacle, it’s the third Radiobutton). You can re-delete unwanted objects afterwards before uploading. Note that all still existing Nodes a deleted way contained before must be loaded in the Layer you’re restoring to (so do not tick “new Layer”) or you will get an unconnected way.
How to do a partial revert is explained on the reverter plugin wiki page:
In order to restore only one accidently deleted way, afair you can also make use of the undelete function of potlatch 1, but this does not seem to be well documented.