BluAge L3 workshop Fleet instance D disk not exists

I am working on BluAge L3 workshop. Everything was going well, until I restarted the fleet. I restarted the fleet for the purpose of restarting the instance. After the fleet was restarted, the D disk in the distance could not be found. I tried type D: in file explorer, which worked before. But now it prompts Windows can't find 'D:'. Check the spelling and try again. I didn't find much resource about this issue. Any suggestions would be appreciated.