Troubleshooting guide
How to fix the problem
In a Finder window, press Command+Shift+. (full stop). The system may contain sensitive files that should not be modified.
If the problem persists
Make sure Finder is the active window and you're pressing a period, not a comma. If the file still does not exist, check the actual location and permissions; don't look for a fix by deleting the contents of Library.
Request a repair