You have installed the Windows 10 upgrade and since then your media files and links no longer open with your usual apps. They are instead being managed by apps that comes pre-installed with new OS (Groove Music, Movies & TV, Photos and Microsoft Edge). Well, if you are wondering how to set your default apps in Windows 10, then you have come to the right place. Click on Start > Settings > System > Default apps > Choose your default apps and configure your settings:

You want Windows 10 to automatically open your photos with Paint? Then simply click on the app that appears below Photo Viewer and select Paint from the list:

Repeat the operation to set your default calendar app, email client, video player and web browser. You can also choose to manage default apps by file type (extension) or protocol:

Right-click on a file to open the contextual menu, select Open with > Choose another app:

A list of compatible apps will be displayed. Select the app you want to use as default app, tick the Always use this app to open ile_extension files and then click on OK: