The program is not printing the first character of the string while using recursion function.

Quote:

The program is not printing the first character of the string while using recursion function.

Your code do not behave the way you expect, or you don't understand why !

There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

The downside of this solution:
- It is a DIY, you are the one tracking the problem and finding its roots, which lead to the solution.
The upside of this solution:
- It is also a great learning tool because it show you reality and you can see which expectation match reality.

secondary effects
- Your will be proud of finding bugs yourself.
- Your learning skills will improve.

You should find pretty quickly what is wrong.

Debugger - Wikipedia, the free encyclopedia[^]

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]
1.11 — Debugging your program (stepping and breakpoints) | Learn C++[^]
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.

As pointed out by Rick ++str is the mistake. The trick is passing (str+1) to the recursive call, try:

#include<stdio.h>

#define MAXLEN 30

void print_reversed(const char *str);

int main()
{
  char str[MAXLEN];
  printf("Enter a string:\n");
  fgets(str, MAXLEN, stdin);
  print_reversed(str);
  printf("\n");
  return 0;
}

void print_reversed(const char *str)
{
  if ( *str=='\n' || *str=='\0') return;
  print_reversed( str + 1);
  printf("%c",*str);
}