Can't import .mod files into Premiere Elements 9

You're using a relatively ancient camcorder format on a very old version of the program -- but on a 64-bit Windows 10 machine.

That may or may not be why it's not working, but these are definitely contributing factors. Which I'm sure you've figured, since the program used to work on your older computer. Among the other contributing factors is the fact that older versions of the program activated certain components the first time you used them -- and, since most of the web systems that activated these old components have long been taken down, it's possible that there are vital components in your old program that simply won't fully deploy.

But that said, have you got Quicktime 7 installed, per the program's system requirements?

Version 9 requires you to manually set up your project when you first start a project. When you did that, which project settings did you select? If you don't remember, go to the Edit menu and check under Project Settings.

If we can determine that you've got everything in place and properly set up, one simple workaround may be to change your video files' suffixes from .mod to .mpg. MOD files are essentially MPEG files, so this may trick the program into recognizing the video.