No music, video or wifi after unroot?

[anon(9212013)]

I reset the flash counter and installed the stock firmware onto my Galaxy S4 (i337m) and now my phone runs extremely slow. It is unable to play any videos, unable to play music, youtube and similar apps crash when I try to use them and i am totally unable to turn on wifi. I would like to know how i can get my phone running smoothly again. Thanks!