How do I raise an event via reflection in .NET/C#?

Here's a demo using generics (error checks omitted):

using System;
using System.Reflection;
static class Program {
  private class Sub {
    public event EventHandler<EventArgs> SomethingHappening;
  }
  internal static void Raise<TEventArgs>(this object source, string eventName, TEventArgs eventArgs) where TEventArgs : EventArgs
  {
    var eventDelegate = (MulticastDelegate)source.GetType().GetField(eventName, BindingFlags.Instance | BindingFlags.NonPublic).GetValue(source);
    if (eventDelegate != null)
    {
      foreach (var handler in eventDelegate.GetInvocationList())
      {
        handler.Method.Invoke(handler.Target, new object[] { source, eventArgs });
      }
    }
  }
  public static void Main()
  {
    var p = new Sub();
    p.Raise("SomethingHappening", EventArgs.Empty);
    p.SomethingHappening += (o, e) => Console.WriteLine("Foo!");
    p.Raise("SomethingHappening", EventArgs.Empty);
    p.SomethingHappening += (o, e) => Console.WriteLine("Bar!");
    p.Raise("SomethingHappening", EventArgs.Empty);
    Console.ReadLine();
  }
}

In general, you can't. Think of events as basically pairs of AddHandler/RemoveHandler methods (as that's basically what what they are). How they're implemented is up to the class. Most WinForms controls use EventHandlerList as their implementation, but your code will be very brittle if it starts fetching private fields and keys.

Does the ButtonEdit control expose an OnClick method which you could call?

Footnote: Actually, events can have "raise" members, hence EventInfo.GetRaiseMethod. However, this is never populated by C# and I don't believe it's in the framework in general, either.