problems with codecs

i have nice 5.1 surround sound logitech speakers (right now im only using 3 front ones, back 2 dont go as far as i want them to) and sound blaster audigy sound card on my computer and recently i was trying to convert videos to my ds lite but the video converter said i needed this k-lite pack codec. it screwed up my sound and now the right speaker is more quite (id say about 50%) and the middle speaker doesnt even give off any sound. on top of that it didnt even fix my conversion problem (until after i uninstalled the codec -_-). i then hooked the speakers up to my ps2 and it worked flawlessly so i know its not the speakers. what can i do to fix it?