The problem is the SkinInfo.xml file, if it's not showing in the preferences panel while you're editing it then you've made some sort of syntax error in this file.
EDIT: In future you should always make sure you have a backup of your last working version (at least) of all files
. Skins are very sensitive and can always end up failing to work for one reason or another, and at times it may be difficult to reverse your actions without a backup.