How does Gintoki's wooden sword get fixed again after getting broken so many times? We've seen Gintoki's sword being broken multiple times and the sword is made of woord, a special kind of wood.

So how does it return back to normal again and again?
It's revealed in the series how his sword is "fixed":


   "Whenever one breaks or is stolen, Gin replaces it by purchasing it through a TV shopping program, asking them to inscribe "Lake Toya" on it prior to delivery" (Source: Gintama Wiki). 


Scene where the process described above is shown (spoiler alert): Youtube