Guest Access’ allows for sharing printers & data amongst networked computers without the nuisance of user names & passwords.
It is easy to turn back on. At each Windows 10 workstation-
Right click Start 
Select either Command Prompt (Admin) or Windows Powershell (Admin)
At the resulting screen copy and paste these three commands:
net user guest /active:yes
REG add "HKLM\SYSTEM\CurrentControlSet\services\FDResPud" /v Start /t REG_DWORD /d 2 /f
exit
And then restart that workstation