Without proper details about your project, system specs and otehr info nobody can even guess. And you could at least have chosen a descriptive thread title.
Actually when I go for collect the files...i go to collect button and the collect box appears...but after when I Click the collect button in the collect files box..nothing happens......I have tried with different setting...like ..for all comp, all...but it remains unchanged...I have more than 150 gb free space in my c drive(system drive) and more than 50 g in my project drive..please have a solution....2/3 months ago I have collected my files from this machine but now it is not happening....I don't know why it is happening??
I am waiting for your answer..
You are still not providing any of the requested info like what system you are on, what footage you use and so on, so we realyl can't know. The collecting proccess not even starting could well mean that your source footage is too much or it's stored in an unfavorably complex folder hierarchy, but this could just as well be some effect in a single comp in the project. Start by weeding out the unnecessary parts with Consolidate and Remove Unused Footage and also flush the caches, then check all your comps.