In OS X 10.9.3, turning on Find My Mac will result in “Users” folder to be hidden.
According to many reports, iTunes 11.2 must also be installed in addition to “Find My Mac” enabled in OS X Mavericks 10.9.3 for this bug to execute.
To make the “Users” folder visible again until next reboot,
login as an administrator, launch Terminal.App and type the command:
sudo chflags nohidden /Users
Type in your password when prompted. If you do not have a login password for your admin account, leave it blank.
By the way, why didn’t you assign a password to your admin account? Set a password already.