Welcome to the forums annieO.
Will the drive read dvds of any kind? DVD drives have two different lasers, one for dvds and one for cds, so it is entirely possible that the drive has suffered a partial mechanical failure.
You should try a different burning program, just to rule out a software glitch of some kind. I suggest using ImgBurn, since it is free to download and use and will not conflict with Roxio.
You can find it here: www.imgburn.com Do a simple data burn to a dvd with ImgBurn and see if it works. If it does not, then please just copy and paste the log file from ImgBurn here in your thread. You can find the log file by clicking Help in ImgBurn, then ImgBurn logs.