Question

if u know usb, can protocols using pic or arm processor help me ,,,,,

Answer 1

yes! Theoretically speaking any controller could do it for you. however there are specialized pic controllers available for USB interfacing itself, using one of them might make life much easier for you :)

Answer 2

i just want to do communicate with pc or with some usb enabled devices ........ just help me in coding ,

Answer 3

well its not really going to be easy... The ease of access USB provides is implemented by a very complex and strict protocol. That being said modern ICs and freely available code could bear a significant part of the pain for you. if you still want to move on please post so, i'll provide few small tutorials.
For simple generic purposes you can use FT232 or FT245 or some other chip from ftdi chips ( http://www.ftdichip.com ). The choice of chip solely depends on what you are creating using USB..

PS: There are many similar chips in market you could pic up any of them.