Help Samsung Galaxy S1 issues with connecting, locking and deleted phone contacts

[allymarell]

Please help!
I've had the Samsung Galaxy s for a year and a half (I've still got about 5 months on my contract) with hardly any issues). Yesterday, I discoverd that my phone had turned itself off.
When I turned it on:

• all the apps I had on the home screen had disappeared and gone back to factory settings, but the background I had chosen was still there. In the apps menu, they had rearranged themselves into alphabetical order (which is fine, but it wasn't like that before). All sound settings and display settings had gone back to factory settings.
• I cannot lock the screen - the screen turns off automatically after 30secs, as per settings, but when I select any of the locking settings, it saves but does not work. It's too easy to turn the screen back on again and press random things and anyone can get in to my phone.
• it wouldn't recognise the 3G network, but when I go to the Wifi /network settings, it says that the data package was activated. Wifi works.
• when I press the power button, it only gives me 'power off' option. It used to also have activate network data, and silent mode, and something else I can't remember.
• all the contacts I had saved to the phone were gone, as were all the saved messages/conversations. The contacts on the SIM were still there, and pictures and files I have saved to the external memory were fine as well. Levels I had gained in games were still there too. Books I had downloaded in Aldiko ebook are gone.

So far I have tried rebooting, taking the battery out and rebooting, and turning settings on and off, but nothing has worked. I don't really want to do a factory reset, but if I have to, most things are backed up. the only thing I did differently recently was download a Traffic update app.

Any suggestions or explanations? Thanks!

 

[allymarell]

I also discovered that I cannot receive calls. Apparently it goes straight to voice mail, and there is no record of a missed call and nothing in the log. The phone was on.