string pangram = "The quick brown fox jumps over the lazy dog";
string[] words = pangram.Split(' ');
string[] new_words = new String[words.Length];
int counter = 0;
string new_pangram;

foreach (string word in words) {
    char[] temp_chars = word.ToCharArray();
    new_words[counter++] = String.Join("", temp_chars.Reverse());
}

new_pangram = String.Join(" ", new_words);
Console.WriteLine(new_pangram);