First, go to your returned petz folder, then take out the wanted pet's file and move it to your desktop. Then go to your adopted petz folder and move the wanted pet's file and move it to your adopted petz folder. Open the game and the pet should be there. Hope I helped!
Open catz/dogz Play on in for about 20 minutes or just leave it for 20 mins. Close catz/dogz. Go on Adjust date and time and put it 1 day forward, then set your time forward about 2 hours. Re open catz/dogz When you bring out a pet, click on the pink or blue icon next to its name and it will tell you stuff about it. If your pet was 2 days old when you did the cheat it should be an adult.