Hi!
Did you get the c:\Windows\system32\config\systemprofile\dekstop not available or accessible ??
Most of people who encounter this issue have a third party anti-virus that have conflict on Windows update (1803)
We'll try to create that desktop folder that is missing on your computer
Try to open task manager and click on File>run new task
Type in: CMD with Administrative privilege
open the folder location using this command
cd config\systemprofile
then press enter
Create "Desktop" folder using this command
MKDIR Desktop
Press enter then restart the computer
* As much as possible use an Ethernet/wired connection
If this steps wont work you can reset the computer with keep all files option from Windows recovery (You can tr the SHIFT+ RESTART procedure)
HOW TO RESET COMPUTER: https://support.microsoft.com/en-us/help/17085/windows-8-restore-refresh-reset-pc
Regards,
Luigi T.