In order to hard reset a Sony Ericsson M608, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Sony Ericsson M608 device will be brought back to the default configuration of a brand new device.
1. Install the official Sony software called PC Suite.
2. Handset must be turned on to perform this operation.
3. Start the application and plug your phone to the PC.
4. Open Tools and select Phone repair.
5. Select your phone's model. Follow the on-screen instructions.
6. Allow the phone to reset and restart. Done.