Assuming you still have the owners manual, take a look in there. You'll find a four digit code which you input by putting the key in the drivers' door and turning it - say the code was 1234, that would be one turn one way, two turns the other, then three the first way, etc.
Unfortunately I can't remember which way to turn the key first, so my having made a note of said code to keep with me might not help...
