He runs the Gladstone Wheelwright Shop, which is opposite the sign.
"It's very inconvenient, it's like we've got half a Scrabble set now. We'd like them back because it will cost a lot of money to replace them."
Mr Lang said a set was worth $700 and the Gladstone community had donated the money to pay for them. "The people who took them have no understanding of how valuable they are to the community.
"The sign gets used for everything, we even had a marriage proposal on it. It had 'Jen, will you marry me?"'
He said the sign worked, too, as Jen said yes.
It promotes everything in the district from rugby games to fairs and is changed every week. The letters were relatively new as they had recently been replaced because of wear and tear, said Mr Lang.
The sign had been advertising the annual Scarecrows Big Day Out, which takes place on November 9 at Gladstone School.
Mr Lang said someone could easily slide the letters back into the sign, no questions asked, or if anyone had any information on where they might be, they could contact him.
The letters had never been stolen before but sometimes they would be taken out of the sign and thrown further down the road, Mr Lang said.
The culprits could have been some teenagers, he said. He hopes they would be returned or else the community would have to fundraise for more letters. "It would be really cool to have them back."