There is an exe inside the Windows operating system that many people do not know about, it is called:

TaskList.exe

It is a command line utility which means you will go to a "Command Prompt" (old term "DOS Box") to use the utility.  You can type:

Tasklist.exe /?

For a list of parameters.  I will not go into the features here as there are quite a few things possible for locating and displaying processes running locally or on remote machines.

The feature I most use is the ability to find all the processes that have a specific process locked.  At times I will try to delete a file and ge the message that it is in use and cannot be deleted.  Other times, will need to update a file and get the same message.

The answer is simply:

Tasklist.exe /M <file name of locked file>

This will show you all the files that have a lock on your target file.  If you leave the file name off, it will give you a list of all running processes and the list of modules they are currently using.