The only thing you can do quickly is generate a new set of private and public key sets and replace the public keys on the servers you are trying to access, however, to do this you must have physical access to the servers that you had the public keys stored on before.
If you don't have physical access to the machines it will be virtually impossible for you.
Also, even if you have physical access to the servers, if the hard drives or the area where the keys were stored are encrypted, again, it will be virtually impossible for you.
Doug Pan
