Sony Ericsson :: Elm - Inbuilt Themes Erased After Restored To Factory Settings

I had purchased a Sony Ericsson Elm (J10i2) mobile last week. I found the mobile to freeze often and so, had to manually remove the battery in order to get it working. So, when I took it to the vendor, the person restored my phone to factory settings. But after this resetting process, all of my Sony Ericsson in built themes like GreenHeart got erased from the mobile except for Flow theme. I am aware that restoring to factory settings restores the phones to it's defaulted features and settings. But how come do the inbuilt themes get erased as well?