Seems you have the Windows Wallet. Just get the Addresses from the Addresses Tab in the Wallet. Then proceed with the other steps.
Actually I tried that, every single address =
"
14:15:43

Private key for address 8N8ySmaNMeqLsEdzBzigVHMfBaf4xS8vTr is not known (code -4)
14:15:59

dumpprivkey 8ePeoUrCBzJLsnfiM2azy9rzRkCgHDohPq
14:15:59

Private key for address 8ePeoUrCBzJLsnfiM2azy9rzRkCgHDohPq is not known (code -4)
"
I fixed it, I had an old wallet backup, used that and it worked.
If my wallet had been encrypted, I would have had to type 'walletpassphrase [mypassword] [number of seconds to keep pass in memory]
But thanks anyways.