Find out what files, registry keys and other objects processes have open, which DLLs they have loaded, and more. This uniquely powerful utility will even show you who owns each process.
There is a built-in function in Windows that shows you what files on the local computer are open/locked by remote computer (which has the file open through a file share):
To see the open files for a process, select a process from the list, select the View->Lower Panel View->Handles menu option. All of the handles of type "File" are the open files. Also, a great way to find which application has a file open
When you see the error "The process cannot access the file because it is being used by another process," you can use several built-in or free tools to find out which process is locking the file or folder.
Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded. The Process Explorer display consists of two sub-windows.