well, so with nanowallet it's not possible import a wallet with a private key? Well, that's really strange. Now i can't check because i'm not home, but i will check later.
Yes you can import Private Key very easy. The password is encrypted in the full wallet data. When creating a new wallet, you should back up private key, password, and full wallet data.
The safest way to do this is to copy it into a simple text program, print it, and put it in a fire-resistant safe.
If you lost your password, you might be able to brute-force it. Any information regarding which characters were used would be helpful. - So if you don't know exact password, but some idea of what it might be, write down those ideas before forgetting.