Hard reset means to reset your phone to the settings and features which were accompanied from the company or at firmware update instant.
Samsung Galaxy, whether Spica or i7500, is very easy to reset! Firstly just power off the mobile phone, restart it by holding volume down + call + end call. Then it will take you to recovery screen where you can switch to home tab for factory reset.
Another simplest way to achieve hard reset is entering *2767*3855# in dialpad and hit dial! this will help definitely!