internal sd card became readonly

after updation of lolypop with cwm 12.1 nightly on SAMSUNG GT-9100 , internal sd card became read only.... cant delete ant of he media from internal sd....but a option was seen..when applications are loading after boot...a time window is there allowing to edit media for 10-12 seconds... as soon as all are loaded it turns ibnto readonly... a member sugested me to load kernal...but i nearly got lost on internet looking for one..as every link provided by sources further provide more links....... plz plz help me out.... its a requet as i use phn for surfing and learing new things and to get knowledge..am not in condition to buy a new phn ..so its a humble request to respected members to guide me and help me out...thanks in advance