Hi lizzy1,
I feel it is next to impossible that someone hacked into your account to delete or steal your store design. If your customized store settings are not exhibited by your Auctiva store, it is likely that they were not saved.
For further assistance with this matter, I suggest you file a support request using the appropriate link on our help page:
http://www.auctiva.com/free_auction_software_help/help.aspx
-Mike