You don't say how old the car is, but if it's the very latest Corsa, they are difficult to gain access to. I have done it, but it took me approximately an hour to do. I didn't damage the car in any way. I can't place the information on here for obvious reasons. The easier way is to take your registration document and some other I.D to your local dealer. They will supply you with a code number. Take this to a (good) local locksmith, and he can cut a key for you if the dealer can't. It may not start the engine, but it will get you in.