The VIN sticker should be under the glove box on the right front side of the vehicle.
If that one is gone and you had it registered it would be on your registration card. The dealer and BRP should have the VIN on file if you bought from a dealer? If you bought it second hand you will need the name of the previous owner to get it from BRP.
I take a photo of the VIN # etc. when I get the vehicle that way I can reference the photo when buying parts etc.