Any Ideas?

[Joe Shmoe]

I have had a Sony Ericsson k510i mobile phone for the past two years and up until recently I had had no problems with it. The problem began when the phones screen went white then came on again. this happened a couple of times but I thought nothing of it but on Friday morning when it did this all themes had gone back to the default setting and half my pictures and wallpapers had disappeared or those there would show a black screen if I tried to open them. I thought that if I turned it off then on again that might help but it would not come on again. I removed and replaced the battery and checked the sim card . The screen gave three white flashes and nothing more. Before it went the battery icon showed a full charge and a charge lasted roughly a week. The phone was kept in a good condition. Any ideas. or is it time for a new one?