Mediacom phonepad g530 Sdcard problem ?

Hi.
(I'm i only speak english /bosnian sry for no italian xD)
Okey, i have a problem on my mediacom phonepad g530 with sd card.
My sd card is good 16gb memory i mount in tablet and work, i mount in my mobile mediacom and work and when my mobile go on sleep mode or loock and i go unlock screen i have notffication for this. SD CARD IS UNMOUNTED i restart phone and sd card is work, when again lock and go sleep mod again error unmounted :(

I'm reset factory mod, and not fix.
My mobile is root how to fix this or install new cwm ?
android: 4.2.1
Can i have install 4.3 or 4.4 on my mobile and how ? please help guys :(