Cannot open R4 Card

my son had 70 games on his R4 card, he deleted 2 of them on the PC, he assures me he only deleted the games and not any folders.However when he loads the card into his DS, There is a Red triangle in the top screen saying "Menu" and a ? above it.he cannot Access any of the games, Has anyone had the same problem and if so how did you resolve it ?

Just reload the firmware back onto the card, backup the games and sav files, format and reload firmware.My brother told me the same thing, turns out file corrupion AND he did delete more than he told me initially.