Welcome to the Community,
which host OS and VMware Workstation version do you use? Is this an issue with booting from a CD or reading the CD from an already installed guest OS (which guest OS do you use)?
Did you make sure the virtual CD-ROM drive is "Connected" (e.g. "Connect at power on" enabled)? In some cases it might be required to enable "Legacy emulation" in the "Advanced..." CD-ROM settings.
André