Default There was a problem communicating with google servers. Try again later.

my phone stoped sync. google calendar (if I click to settings - account - I see there all sync app like gmail, Play, Books,... but here should be also calendar, but it isnt here..)
I found some forum and app "PrebuiltGmsCore.apk" sould helped, but It is impossible to insstaled it..

So does anybody some next tip?

Thanks a lot!