A pair of small working speakers (Nailsea BS48)

I had a pair of Pioneer speakers i think that was their make that worked perfectly but i decided I'd like a pair of smaller speakers so a friend swapped her small speakers in exchange for my speakers, however after connecting them to my panasonic music system they didnt work, sounded as if they had been blown. My friend didnt answer my phonecall. So if anybody has any smaller speakers i can kindly have id be very grateful.