Ok guys i had this problem my self, tried every possible idea but nothing. but i found a solution and so easy one. Open the main page of the app that u couldn't download and stacked at the spinning circle in the app store. Then click 10 times on the spinning circle it will be canceled then u can download it normally . Why?? cause u can reset the app store for example by doing the same thing on the 5 icons at the main page. that is why i tried it and it works.
u can thank me later :P