Had this happen when i changed the battery on my truck,i searched the web and found a site that provided a 1-800 number and about 5 dealer codes,only one of the dealer codes worked,but by following the instuctions it gave me my reset code no problem,it was a long time ago so i dont remember where i got the site.
BTW:if you go aftermarket let me know if you want to sell your old unit,mine has volume button issues.