I wanted to send my iPhone contacts to Google mail and transfer back to my new Samsung Android.
After changing iTunes setting "sync address book contact"-> "sync google contact", no new contact appear in my new Google Mail account and all my contacts on iPhone have been ERASED.
Why has this happened?
Best Answer
What you have done is chosen to include "only" your Google Contacts for syncing with your iPhone via the iTunes sync.
What I would recommend is that you look at setting up the Google Calendar sync within the Address Book application on your computer, and then copy the records manually between accounts (either via a drag and drop or copy and paste) on your computer.
Once this is done, the contacts on your computer should reside on your Google Contacts, as well as be synced back to your iPhone the next time you sync it with iTunes.
Additionally, you can set up your gmail account under your iPhone using the Microsoft Exchange connector (server name: m.google.com) with your Google credentials, after which your contacts will automatically be synced between your iPhone and Android devices without having to sync via your computer.