Slash commands?

[myonghwan_eiselstein]

I accidentally disabled my Zygor guide and now I don't know how to reactivate it. Are there slash commands for this?

[Cartman]

You can either click the minimap button or use a keybinding to toggle the guide (wow keybindings, look for the Zygor section).
If this does not help make sure the guide is loaded for that character, you can disable addons for particular characters and may overlook this as only the color of the checkbox in the addons screen changes.
To reset all guide options delete the ZygorGuidesViewer.lua file in the WTF folder. Remember that you'll have to reselect the guide you were on on each character if you do this.