um im sorry to say this but i dont think you will get that game back if your son has pressed the x button on the ds he will have deleted the game permenatly but i know were he can get another copy of the game for free . WARNING the next part requiers a computer this only works if its a computer NOT a laptop go to romsite.net its a website that has many links that are download pages .type in animal crossing on the website and a load of options for the game should show up click on animal crossing and press on one of the folowing buttons that are yellow they will say:download from fileserve ,download from megauplaod ,download from wupload and download from file sonic click on any one of those appart from wupload cuz it never works at all. u can insert ur r4 chip (sd card )into the usb u should have got with the chip put the usb into the pc and it should come up with a small screen on ur pc click that off u dont need that and go to my computer then open removal disk and there shold be a letter next to it like F or G etc.click on it then it shuld show a page that has all your sons games close that down but dont click it off cuz its inportant then got back to romsite.net and go to the link u opened earlier download it from the web link and it should appear in ur downloads open the file and extract it . then cut and paste the game file and put it into the removle disk ur son now he as his new game .

Hope this helps and...enjoy(: