cant play avi or mpg files help!!!

[darkfight]

i accidentally unregistered a filter or codec of some sort now i cant play avi or mpg files only vob and mp3s. i get this error message saying "the source filter for this file could not be loaded". can i fix this??

[darkfight]

i have a sound codec problem seems like when i encode an avi to an mpeg with quenc i get a sound thats not suppose to be there in the beginning of the file. its using the xvid and ac3 dvm codec whatever that ac3 codec is. it seems like now im having an ac3 codec problem i get the Avisynth open failure: acm failed to suggest a compatible PCM format in quenc. any suggestions??