try holding select when powering the system on to see if it has a9lh installed (or putting the decrypt9.bin file on the SD root and renaming it to arm9loaderhax.bin
may also be worth getting in touch with whoever originally modded it for you and asking firstly if they have a nand backup and secondly if they installed a9lh
(PS i know he seems to suggest he was just using homebrew, but he also sounds like he doesnt follow the scene too much so he may not really know what his friend installed for him)