Disclaimer : By performing hard reset, all data on device storage will deleted. So backup your important data first.
Samsung Galaxy Fit S5670 Hard Reset Procedures :
1. Power off phone
2. Press and hold Menu Button + power on for at least 10 seconds
3. Android System Recovery Mode Appear
4. There are 4 options
reboot system now
wipe data/factory reset
wipe cache partition
5. Move the options to " Wipe data / factory reset " using volume down ( - ) button and menu button to confirm, because the touchscreen doesn't work in reovery mode
6. After the process done, phone will reboot.