<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<Style TargetType="Button">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Content">
<Setter.Value>
<Image Source="Images\B.jpg"></Image>
</Setter.Value>
</Setter>
</Trigger>
<Trigger Property="IsMouseOver" Value="false">
<Setter Property="Content">
<Setter.Value>
<Image Source="Images\A.jpg"></Image>
</Setter.Value>
</Setter>
</Trigger>
</Style.Triggers>
</Style>
</Window.Resources>
<Grid>
<Button Margin="70,53,61,58"/>
</Grid>
</Window>
Regards,
Selva Ganapathy K