I don't know. Did you not back up the original files?
Protip: always make a backup of original files when you change something for the first time.
- If you did back up the files you changed, just copy the originals back.
- If you didn't back up the originals but know what you changed (you could even sort by last modified to see), copy the original files from an original archive.
- If you didn't back up, and don't know what you changed, extract the patch Z over your current installation without deleting anything. Then, only the changes will be removed.