I have the Iphone 4, and backed up/synced my phone, and also saved the SHSH blobs with TU, I have modem fw 0.1.59.00. I downloaded a 4.2.1 ipsw file, because I was on 4.0.1, and followed the instructions on iclarified on how to upgrade to 421, and then JB with GP. Everything went well and I saw the loader icon. I then must have done something stupid, either syncing or restoring, which then loaded all my apps and contacts, photos and music, because now the loader app is gone. I restarted the phone and the GP icon came up, but the loader app is still gone after I did another JB with GP. So I'm seeing the GP icon at start up, but not seeing the loader app or cydia. What should I do to get Cydia back on the phone?