Replace similar files in different folders by a different file

For a new project, I encountered a problem where I have one file (items.txt) which occurs in a thousand different folders (including subfolders) that I have to replace with another file (items.jpg). I want to replace all these old items.txt files with a new 'parent' file items.jpg through a simple program. But that's my problem, I don't find such a program. Does someone know such a program?

I thought to have another solution for this problem, but it wasn't. My solution was this: Suppose I search for any files called "items.txt" with the Windows Explorer and then remove it than I needed a program that can fill up all the empty folders and sub-folders with the file 'items.jpg'. But I also did not found such a program.

If there are people who has a solution for one of these problems, in the form of a free computer program, please leave a comment below.

Thanks for your help,
hopefully there will be a solution come out.