After Apple released OS X 10.9.3 yesterday, some users started experiencing a bug that hid their /Users folder. It appears that Apple has released a small iTunes update, numbered 11.2.1, to combat the bug. MacRumors forum member IzzyJG99 notes:
Users can update to iTunes 11.2.1 via the updates tab in the Mac App Store or through OS X’s „Software Update“ drop-down menu.An update just popped up for me. iTunes 11.2.1 in the App Store. When it was done installing it had a little pop up about iPhoto Library. Now the User folder is showing up again.
Original article: Apple Releases 11.2.1 iTunes Update to Fix Hidden ‘/Users’ Folder Bug