Android :: Cant Update Apps In Market - No Error Message

I uploaded the new updates to the application in the market. There was no error message shown. It seemed that the uploading was successful. However, the version name and the app itself were still the old version. FYI: lost the original private key or the keystore file. I generated a new keystore file to sign the app. I also met the minSDK problem and solved it by set the minSDKversion in the manifest file. There must be a way to update the app. I don't want to upload the app as an new application since there is a large base of existing customers.