You lost the only admin key.
Purchase a new key from an authorized dealer.
My son destroyed his dodge key dropping it in school. I found some replacement key/fobs on amazon, went to a local keysmith to cut the keys and program them. They hooked up the computer to his car, and reprogrammed the whole system to a new configuration in the event any other keys were still out there and now would be disabled. Only his new keys are able to work with the car. He bought it as a salvage repair so there was some question as to how many keys were around.