Lost all memory on hard drive

Once it's gone, it's gone.
You can try loading the firmware update from Philips website, but this is unlikely to resolve.

Philips HDD – Reloading the Firmware Hack

1. Plug your GoGear HDD into the computer
2. From ‘My Computer’ right click the GoGear drive and format it. Be SURE you format it as FAT32 and quick compression is not on
3. Create 3 folders on the newly formatted disk called: ‘_System’ , ‘Data’ , ‘Media’
3. Download fom Philips the latest Device Manager for your kind of player
4. Install the Device Manager
5. On the Desktop, right click the Philips Device Manager shortcut, then Properties, then open file location.
6. Copy the folders you see there into the ‘Data’ folder
7. Copy the Firmware.ebn file into the ‘_System’ folder
8. Unplug the device and now it should run fine
-Tha Mp3 Doctor