NEED HELP!!!!!!!!!!!!!!

[Mista CaNE]

MY BOY HAD THE FIRST VERSION OF PRO TOOLS, WITH 9.0 OS ON HIS MAC. HE WAS GETTING BEATS FROM OTHER CATS WHO HAD THE NEWER VERSION AND IT WASNT PLAYING RIGHT, SO HE INSTLLED 5.1 PRO TOOLS AND NOW WHEN HE OPENS HIS OLD SESSIONS THERES SOUNDS MISSING ETC..................WHAT CAN HE DO TO MAKE SURE EVERYTHING IS AS IT WAS, HE CAN PLAY THE NEW STUFF HE WANTED AND DOESNT LOSE ANYTHING????????///