Here are the tools I personally use and most frequently recommend for use with or troubleshooting your CD/DVD drive. All of these tools are free except where noted:
DVD Identifier Can be used to determine the manufacturer of any blank DVD media. Also useful to diagnose the inability of a computer to recognize blank DVDs. If DVD Identifier can read the code, this indicates the drive is functioning properly.
Nero Infotool Another tool for reading blank media and diagnosing drive problems