Before that situation my android phone was transferring data from both ends (mobile to PC / PC to mobile) but from a day before my android phone connected through USB cable and I transferred my data from mobile to my laptop successfully till now. But when i copy data from laptop to my phone, it start processing but not go ahead. I try it on someone tab it is working but it troubling on my mobile. Its not exceeding from the image given below!
Welcome to Android Central! Have you tried using a different USB cable? Is it only that PDF file that won't copy, or does this happen with any file now?