DVD/CD Rom drive plays music OK but no CD/DVD vids

My Pioneer DVD-RW DVR K17LF drive on Toshiba Satelite A215 is OK when playing Audio CDs but does not read DVDs. Diagnostics shows no errors and Harware Manager shows the drive is OK. Reinstalling(deleting the drive and rebooting) the drive did not help either. This problem happened when I changed DVD region several times. Could it be a reason for the failure? What might be a cure for the problem?