Static methods cannot be inherited or overridden, and that is why they can't be abstract. Since static methods are defined on the type, not the instance, of a class, they must be called explicitly on that type. So when you want to call a method on a child class, you need to use its name to call it. This makes inheritance irrelevant.

Assume you could, for a moment, inherit static methods. Imagine this scenario:

public static class Base
{
    public static virtual int GetNumber() { return 5; }
}

public static class Child1 : Base
{
    public static override int GetNumber() { return 1; }
}

public static class Child2 : Base
{
    public static override int GetNumber() { return 2; }
}

If you call Base.GetNumber(), which method would be called? Which value returned? Its pretty easy to see that without creating instances of objects, inheritance is rather hard. Abstract methods without inheritance are just methods that don't have a body, so can't be called.