Many times past owners will change out kitchen cabinets (where you might find a wind zone plate) inside the cabinet door. They don't realize the significance of the data on these sheets of paper that are glued to cabinet surfaces or inside master bedroom closets (that are sometimes painted over) where you would likely find them.
Your first direction to seek help would be the city or county building and zoning in your jurisdiction.. Ask them for your best course of action. Depending on the type of Longitudinal and anchoring systems used for your home, they may let you pass without the wind zone plate.
You may also contact the Department of Highway Safety and Motor Vehicles to see if they can help. They might have records that reveal the home. If they tell you that you must have the wind zone plate, then follow Lowell's plan.