WPF Binding: Static resource cannot be resolved

You're missing this bit:

->this Utility class can be instantiated as a resource<- and then referenced in the ComboBox creation.

It'll look something like this:

<Application.Resources>
    <local:Utility x:Key="monthCollection"/>
</Application.Resources>

This bit:{Binding Source={StaticResource monthCollection}, Path=MonthCollection says to find the static resource monthCollection and on it use the property MonthCollection so you first must instantiate the object which has `MonthCollection as a property and then reference that static resource.

You will probably also need a statement something like this added to the top of your file:

xmlns:local="clr-namespace:YourNamespaceHere"

Untested code below:

<Window x:Class="FaceReport.WindowMain"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:FaceReport"

 Title="Rapor" Height="402" Width="600" WindowState="Normal">

<Application.Resources>
    <local:Utility x:Key="reportCollection"/>
</Application.Resources>

 <Grid Name="gridMain" x:Uid="uidGridMain">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <ComboBox SelectedIndex="0" DisplayMemberPath="Value" SelectedValuePath="Key"  Margin="132,9,200,0" Grid.Row="3" Height="24" VerticalAlignment="Top" Name="cbBind" 
     ItemsSource="{Binding Source={StaticResource reportCollection}, Path=ReportForCollection}" />
 </Grid>
</Window>

Please add an entry like below in app.xaml:

<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
          <ResourceDictionary Source="/Skins/ControlSkin.xaml">
         </ResourceDictionary>
            <ResourceDictionary Source="/Skins/ListBox.xaml">
          </ResourceDictionary>
        </ResourceDictionary.MergedDicionaries>
    </ResourceDictionary>
</Application.Resources>