have lost all access to internet on dsi? help?

hi had a dsi since xmas and been fine could play games, shop and use internet with console, my son has been messing with it, he 3, and all internet access gone no entry to nintendo shop, no search tool and seems all bought games have been deleted, have took out battery hoping to restore factory settings with no change to system. my connection on wifi is fine (nintendo tell me thats the problem) but no way to access net from it anymore! does anyone know how to fix or were i could take it, do games shops fix these things??? thanks for any help greatly appreciated