Can someone give me the code of this program:

Write a program that convert the numbers of length upto 3 into words and speech.Use either if else or switch case only

In C? No. I don't have a Speech API for Windows using just C. So that's a dead end.

How about VBScript? Kind of easy there.
https://www.instructables.com/id/Text-to-speech-using-VBS/

PS. Why the code limitation. IRL, no one does that except homework which you should reveal up front.