Help!

I must have thought the master skull was clutter, and I have either sold it or dumped it somewhere.
Now I need it, I can't remember where, and I have been round all the merchants but no joy.

Can I use commands to get it back?

Thanks

When I enter my house in the Marketplace, I get the panel of help about placing+moving, but the problem is I can't figure out how to enter/exit 'Build Mode'? When I place something, it is still in 'Move/Place' mode - how do I get out of it? Also, I have a blueprint for a Chest, but how do I build it...