Switch case reviews, finding days of the week that coresponds to a number given
I would add to forsvarir's good answer: start thinking now about the power of abstraction.  Programming is all about building abstractions.  Make your abstractions solve one problem and solve it well.  For instance, here's a problem to solve:

static string Ordinal(int n)
{
    // You fill this in. The method takes an integer and returns
    // 1st, 2nd, 3rd, 4th, etc. 
}


Heres another one:

static string WeekdayName(int w)
{
  // To do: Return the name of the day of the week.
}


And here's another:

static int GetIntegerFromConsole(int low, int high)
{
    // to do: prompt the user, sit in a loop until they give
    // a response in the right range, and return it.
}


Once you have those methods then your program becomes trivial.

int weekdayNumber = GetIntegerFromConsole(1, 7);
string weekdayName = WeekdayName(weekdayNumber);
string ordinal = Ordinal(weekdayNumber);
Console.WriteLine($"{weekdayName} =&gt; {ordinal} day of the week");


You know what I like? Four-line-long programs, that's what I like. Move the mechanisms to their own helper methods, debug those methods, and then rely on them to do their jobs.