LW's media player itself can only play audio. If you're refering to resetting default or making LW media player your player again, go to LW's menu Tools>Options>Player & tick the option box & press apply. This won't take effect until next time you open LW. For video, well ... depends what you want to do. A decent video player is VLC: http://www.videolan.org/vlc/ (choose nearest mirror site) And to change your computer's defaults for which file is played by which program, see Setting Default video app & apply the same principle to whichever file-type you are wanting to change.