C510 Master reset
If you select Reset settings, the changes that you have made to settings will be deleted.
If you select Reset all, your settings and content, such as contacts, messages, pictures, sounds and downloaded
games, will be deleted. You may also lose content that was in the phone at purchase.
To reset the phone
1 From standby select Menu > Settings > the General tab > Master reset.
2 Select an option.
3 Follow the instructions that appear.
When your phone is frozen pull out battery and reinsert it. Turn on your C510.
Restart your C510 phone every day to free memory or do a Master reset.
Use PC Companion
Direct link to PC Companion for C510:
or use old PC Suite
If nothing works: As last resort do a Sony Ericsson phone repaire with PC Suite. USE THIS METHOD FOR hard reset AFTER INSTALLATION----> TOOLS > PHONE REPAIR