You will need to email support@teamlava.com . They will be able to check your game to find out what happened to your gold.
After your clear around the tree twice, then you should get a new goal that opens up to get 10 epic dragons, one color for each building to unlock. No you cannot buy the buildings until you complete the goals.
Since yous started the thread, if I remove your post, it will delete the thread. This is good information for others thay may have the same question so I need to leave the thread open