I want set permission file or folder to nobody can access it. how to deny all users or groups to access any file and folder of document library in share point 2010 ?
In case you do not have access to run powershell or a console application and the items with broken inheritance are limited, you can try the following:
This way, all the items will eventually inherit permissions from the library, which has no assigned permissions for any user (apart from the site collection admin).
Of course it will only work for a limited amount of items with unique permissions. If you have houndreds or thousands of broken permissions (which you should not as it is a bad practice) you will have to use a script.
The same in PowerShell:
And some C# sample:
Go to library permissions -> Stop inheriting permissions -> then select all users and then click remove users permissions.