Postby Dicrostonyx » 14 Jun 2016 23:46
Most likely your default program got changed or deleted in Windows. This happens occasionally when programs update or if you use a different program for a known file type.
In Preferences, on the Interface tab, click the button at the bottom which reads "Set up associations...". Make sure that the appropriate file types are checked, the Save and exit VLC. You may need to rebook the computer, but it shouldn't be necessary.
If you're using Windows 10, you'll no longer be able to do this from within VLC, instead you'll get a message to go to "Settings > System > Default apps". To do that, click the Windows icon in the control bar, then click Settings. In Default Apps, there should be several main default apps showing, such as Email, Music, and Video Player. If Video Player does not show VLC, click whatever is showing there and select VLC from the list of available apps. If Video Player is not one of the top default apps being displayed, scroll to the bottom of the page and click "Set defaults by app", find VLC in the list and click "Choose defaults for this program", then check next to any file type you want to open with VLC, Save, and close all of these windows.