Do a simple system restore first, this will many times solve the issue by putting lost files back and is the first and fastest method. Also, try the network setup wizard again, if not a critical file, simply re-set up by connecting to the work group, etc...and see what happens. If not, you can try start,run, type sfc /scannow and hit enter, go from there. There may be some free file undelete utilities you can download as well to try and get it back.