If you get the new key & it still won't turn, do the "hold the key to a palm sander while turning" trick to get it turned to swap out the cylinder. It worked for me.

__________________
1982 300sd from craigslist $800 greased on one tank with NO CONVERSION in the Hot Texas Sun. (currently dead & awaiting engine damage investigation and/or longblock swap)
new daily: '03 vw 5speed jetta tdi wagon. bagged&chipped