Why did my contacts disappear?

[Android Central Question]

I lost my cell phone recently. Someone found it the same day, and I got it back from that person. Now I have found that my contacts have all disappeared. It's the only thing that seems different about the phone since it was lost. I'm wondering if the person who found it did something to it that caused the contacts to be lost. Should I be worried that something was done to it that has compromised my information?

 

[Aidelis]

Did your phone had a screen lock? If not, he may have went inside and deleted