I have a file format gif I put it in mediaelement, animation worked, but how to make that file was played continuously
You can use a MediaTimeline element to make the animation loop forever:
<MediaElement Name="yourMediaElement">
<MediaElement.Triggers>
<EventTrigger RoutedEvent="MediaElement.Loaded">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard>
<MediaTimeline Source="YourAnimation.gif"
Storyboard.TargetName="yourMediaElement"
RepeatBehavior="Forever" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</MediaElement.Triggers>
</MediaElement>
EDIT: The solution above does not seem to be working with GIF files whose size exceeds a few kilobytes. The issue apparently come from Windows Media Player (it can be reproduced with WMP itself). So, YMMV.