Charwis should have handed you the nugget. It's a normal gold nugget item with a special description, so it's easy to confuse with regular ones unless you hover over it. Maybe you accidentally melted it or sold it?
After you finish the quest, you get to keep the nugget, so there might be a player who kept theirs that can help you out. Otherwise you will have to wait for a GM to log on to aid you. When you see a GM online, you can type !gm and then your message to them to request aid. EG: "!gm I need help with a quest".