public interface ISomeInterface
{
void DoSomething();
}

public class SomeClass : ISomeInterface
{
#region ISomeInterface Members

void ISomeInterface.DoSomething()
{
throw new NotImplementedException();
}

#endregion
}

Type type = typeof(SomeClass);
MethodInfo[] methodInfo = type.GetMethods();

Type type = typeof(SomeClass);
MethodInfo[] methodInfo = type.GetMethods(BindingFlags.NonPublic
BindingFlags.Instance);