Needs no C# code for handling this orientations.
The following xaml code makes change in property values when orientation of the app changed from landscape to portrait view and it will undo the changes when the app comes back to landscape mode.
1. grid view collapse and visible
2. List View font family thickness and vertical alignment
3. Textblock fontsize
4. Grid Row no, Column no, ColumnSpan
5. Button width and height
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="ApplicationViewStates">
<VisualState x:Name="DefaultLayout"/>
<VisualState x:Name="PortraitLayout">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="portraitEventViewModelsGridView">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="landscapeEventViewModelsGridView">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Control.FontFamily)" Storyboard.TargetName="ListView1">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<FontFamily>Global User Interface</FontFamily>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Control.BorderThickness)" Storyboard.TargetName="ListView1">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Thickness>50,200,50,0</Thickness>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.VerticalAlignment)" Storyboard.TargetName="ListView1">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<VerticalAlignment>Top</VerticalAlignment>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="TextBlock1" Storyboard.TargetProperty="(TextBlock.FontSize)">
<DiscreteObjectKeyFrame Value="20" KeyTime="0">
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid1"
Storyboard.TargetProperty="(Grid.Column)">
<DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid1"
Storyboard.TargetProperty="(Grid.Row)">
<DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid1"
Storyboard.TargetProperty="(Grid.ColumnSpan)">
<DiscreteObjectKeyFrame KeyTime="0" Value="2"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Button1" Storyboard.TargetProperty="(Button.Width)">
<DiscreteObjectKeyFrame Value="225" KeyTime="0">
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="Button1" Storyboard.TargetProperty="(Button.Height)">
<DiscreteObjectKeyFrame Value="56" KeyTime="0">
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>