Uh, terri? You have two problems or just one? If you have a problem with .wmv, then my best suggestion would be to simply avoid this troublesome format.
It may also be that the file actually doesn't have an audio track.
As for the .avi problem, yes, something is missing from your computer: codecs.
Just download VLC (
www.videolan.org/vlc/), install it, find your Shared folder (in LW's options, go to Saving and then use your browser to go to the location specified there) and open the file through there (I suggest you always open them like this).
Finally, remember that LW's developpers aren't responsible of the files shared in Gnutella: we, the users are. The step-by-step (ooh babeh! ugh) guide they provided is easy but it doesn't guarantee that the files you'll get will all be perfect (as you no doubt noticed
)