You Cannot View the Files on a Disc After You Replace a CD-R or CD-RW Drive with a DVD or CD-ROM Drive (Q311455)

On a computer (such as a notebook computer) in which you can replace the CD-R or CD-RW drive with a DVD or CD-ROM drive, you may not be able to gain access to the files that are on the disc that is in the DVD or CD-ROM drive if you replace the CD-R or CD-RW drive with a DVD or CD-ROM drive while the computer is off and then start the computer. When this occurs, you can still gain access to the files by using a command prompt.

This problem occurs if you replace the CD-R or CD-RW drive with a DVD or CD-ROM drive while the computer is off and the same drive letter is assigned to the new drive.

When a writable drive such as CD-R or CD-RW drive is installed, Windows Explorer records its drive letter in the registry. If you replace the CD-R or CD-RW drive while Windows is running (this is known as “hot swapping”), the registry information is automatically updated. However, if you replace the CD-R or CD-RW drive while the computer is off, the registry information is not updated and Windows Explorer tries to treat the new drive as the writable device.

Click here for the article.