Contacts disappeared in LAVA Iris, how can I get them back?

[AC Question]

Contacts disappeared in LAVA iris

Hi sir
I am purchasing LAVA IRIS atom 2,
When browsing internet in mobile at that time all contact are disappeared,
After Re start mobile they are shown, i am reset mobile 3 to 4 times for this problem
again this problem came.

What is the problem?
Daily 3 to 4 times it will be happend,
I am disapponted this problem
Pease solve it,

Thanks