Why did the phone address book and phone records suddenly disappear and nothing was done?

I think of several possibilities for your reference:

1, the mobile phone has a virus.

2. Delete it when others are playing with your mobile phone.

3. There is something wrong with the 3.sim card.

This is more likely, but it is a bit verbose. Be patient: did you take out your card and put it on another mobile phone before? Some mobile phones have a function when you put on a new card, which is to copy or move the phone book in the sim card to the mobile phone. If you press Enter, the phone book in the sim card will be lost. Or sometimes two mobile phones are not compatible.