Since you have just replaced the device with a new one, the first thing you should do is make sure that the hard drive has been placed back into its casing correctly, is properly connected to the sata slot and screwed back into place to avoid bumping it out. The next step would be to enter into the computers BIOS and make sure that it is detected, then change your boot settings so the computer will try to boot from your operating system disk. As long as you can see it in the BIOS, you should be good to go, otherwise you have have swapped one bad drive for another.

If it's missing from the computer, either the drivers or missing or there is a loose/lack of connection between the device and the computer. You could try reinstalling drivers from the toshiba site for the dvd drive; however, if that doesn't work, verify that the drive has been properly inserted into the laptop and secured via it's screw.