Well you missed his point entirely.
// flip X
sprite.setTextureRect(sf::IntRect(width, 0, -width, height));
So your code should be:
Flipped along the x axis:
pSprite.setTextureRect(sf::IntRect(21+9,7,-21,38));
Flipped along the y axis:
pSprite.setTextureRect(sf::IntRect(9,38+7,21,-38));
Both:
pSprite.setTextureRect(sf::IntRect(21+9,38+7,-21,-38));