(HELP) my sgsa can't mount storage/sdcard0 n can't flash official firmware

for the first problem is invalid imei,i try anything to fix it but didn't succes,n then i try to flashing firmware 412 but failed at modem sesion, i try to downgrade it but failed at repartition session,try to another pit but it same,n a try to flashing twrp is succes n flashing custom rom,but the next problem is can't mount storage/sdcard0 mp3 player n camera notification is insert ext sdcard,,,help me,,, sory if my english is bad,,,i'm from Indonesia

from xda-developers http://ift.tt/1QyXUAR
via IFTTT