I can't open my 'manage storage' what to do?

I cant open 'manage storage' it loads first but then it stops after 1 sec, nothing happens. I need to chekk what i have on my iCloud so i can delete some things so i can copy my iPhone on it. But i can't do it because i can't go in on 'manage storage'... Is something wrong with my iPhone or wrong with iCloud..? i updated my iPhone to the last iOS but still doesn't want to work. what should i do?