Under the old user account:
First, create a restore point by hitting Start and typing, create a restore point, click the create a restore point option that pops up. When it opens, look at the bottom of the window and click the create button, name it whatever you wish, and let it finish.
Open an elevated command prompt by clicking Start, type cmd, CTRL+SHIFT+ENTER. An elevated command prompt should open, in this command prompt copy and paste this:
icacls "C:\Users\yourusername\Desktop" /reset /t /c /l Replace yourusername with your computers user name. Hit enter.
Let us know how it goes.