change drive letters f.e. CD-Rom win7

Use the helpfully tool diskpart

so you can use with awnser-file or direct by command:
open CMD with administrative rights
“diskpart.exe”
“select volume 0” (this ist the CD-Rom volume, you can show it by “list volume”)
“assigen letter=z”

if you need more informations about diskpart type “help”
or look at microsoft artikel

one more can be helpfully, you would like to show all drivelettes first on youre Win-Explorer
you can set a reg-hive:
reg add “HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\ShowDriveLetters” /v CheckedValue /t reg_dword /d 0x4 /f

have fun and no guarente