If you configured your SSH passphrase with the OS X Keychain, you may be able to recover it.
- In Finder, search for the Keychain Access app.
- In Keychain Access, search for SSH.
- Double click on the entry for your SSH key to open a new dialog box.
- In the lower-left corner, select Show password.
- You'll be prompted for your administrative password. Type it into the "Keychain Access" dialog box.
- Your password will be revealed.