Change jpeg icon

For some reason, in my installation of Directory Opus, the icons for jpegs (or any image file for that matter) have gotten changed to some generic, nondescript icon that looks like something you would you for a txt file. It doesn't match the icon used in File Explorer (not that that matters). I need to get the icons for image files changed to something more appealing and recognizable.

How do I accomplish this?

Thanks,

Right-click a JPG, then use Open With > Choose Default Program and select the one you want. That will usually fix things like that.

Alternatively, right-click the file and click "properties". The "General" tab shown you the default application for that filetype. Click "Change" to select a different application as default, and you'll get a list like in Leo's solution.
Major difference is that this change is permanent, while Leo's requires you to check an "Always use this app..." to make it permanent.