How can I wrap text in a label using WPF?

The Label control doesn't directly support text wrapping in WPF. You should use a TextBlock instead. (Of course, you can place the TextBlock inside of a Label control, if you wish.)

Sample code:

<TextBlock TextWrapping="WrapWithOverflow">
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec adipiscing
    nulla quis libero egestas lobortis. Duis blandit imperdiet ornare. Nulla
    ac arcu ut purus placerat congue. Integer pretium fermentum gravida.
</TextBlock>

Often you cannot replace a Label with a TextBlock as you want to the use the Target property (which sets focus to the targeted control when using the keyboard e.g. ALT+C in the sample code below), as that's all a Label really offers over a TextBlock.

However, a Label uses a TextBlock to render text (if a string is placed in the Content property, which it typically is); therefore, you can add a style for TextBlock inside the Label like so:

<Label              
    Content="_Content Text:"
    Target="{Binding ElementName=MyTargetControl}">
    <Label.Resources>
        <Style TargetType="TextBlock">
            <Setter Property="TextWrapping" Value="Wrap" />
        </Style>
    </Label.Resources>
 </Label>
 <CheckBox x:Name = "MyTargetControl" />

This way you get to keep the functionality of a Label whilst also being able to wrap the text.

I used the following code.

    <Label>
        <Label.Content>
            <AccessText TextWrapping="Wrap" Text="xxxxx"/>
        </Label.Content>
    </Label>

You can put a TextBlock inside the label:

<Label> 
  <TextBlock Text="Long Text . . . ." TextWrapping="Wrap" /> 
</Label> 

To wrap text in the label control, change the the template of label as follows:

<Style x:Key="ErrorBoxStyle" TargetType="{x:Type Label}">
    <Setter Property="BorderBrush" Value="#FFF08A73"/>
    <Setter Property="BorderThickness" Value="1"/>
    <Setter Property="Foreground" Value="Red"/>
    <Setter Property="Background" Value="#FFFFE3DF"/>
    <Setter Property="FontWeight" Value="Bold"/>
    <Setter Property="Padding" Value="5"/>
    <Setter Property="HorizontalContentAlignment" Value="Left"/>
    <Setter Property="VerticalContentAlignment" Value="Top"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Label}">
                <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true" CornerRadius="5" HorizontalAlignment="Stretch">
                     
                    <TextBlock TextWrapping="Wrap" Text="{TemplateBinding Content}"/>
                </Border>
                    
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Instead of using a Label class, I would recommend using a TextBlock. This allows you to set the TextWrapping appropriately.

You can always do:

 label1.Content = new TextBlock() { Text = textBox1.Text, TextWrapping = TextWrapping.Wrap };

However, if all this "label" is for is to display text, use a TextBlock instead.

We need to put some kind of control that can wrap text like textblock/textbox

 <Label Width="120" Height="100" >
        <TextBlock TextWrapping="Wrap">
            this is a very long text inside a textblock and this needs to be on multiline.
        </TextBlock>
    </Label>

try use this

lblresult.Content = lblresult.Content + "prime are :" + j + "\n";

 <Label x:Name="datetimeofmsg" 
           HorizontalAlignment="Left" Margin="4.286,55,0,0" 
           VerticalAlignment="Top" Background="{x:Null}" 
           FontWeight="Bold" Width="61.714" Height="20" Foreground="White">
        <Label.Content>
            <AccessText TextWrapping="Wrap"/>
        </Label.Content>
    </Label>

I used this to retrieve data from MySql Database:

AccessText a = new AccessText();    
a.Text=reader[1].ToString();       // MySql reader
a.Width = 70;
a.TextWrapping = TextWrapping.WrapWithOverflow;
labels[i].Content = a;