I need help with my iphone

Hello,
kindley, i need your urgent help.

when i copy a pdf file from my pc and paste it in my iphone it never could be see it or open it( when i open my ebook icon it's appear empty).
i tried to download any version of pdf for iphone but it keep refusing to be installed.

can anyone send me a link to download the pdf for iphone and some books to see if it works?
thank you all

you prompet respond is highly apprciated.