Validate that a given string (name) meets certain requirements
As you wanted to use RegEx I have a recommendation for you:

public static bool IsValidName(string Name)
{
    if(String.IsNullOrEmpty(Name))
        return new ArgumentNullException();

    string pattern = @"^[0-9]{4} [0-9]{2} [0-9]{2} abjwg kelk\\.exe$";
    return Regex.IsMatch(Name, pattern);
}