Menubar and Finder icons missing
I restarted my laptop into safeboot by holding the shift key. Then I logged in while holding the shift key. After a restart the icons were back.
The whole procedure is described here: https://discussions.apple.com/thread/6738097?start=0&tstart=0
Two options I can think of:
1) Clear the Finder's icon cache, from Terminal, & rebootsudo find /private/var/folders/ -name com.apple.dock.iconcache -exec rm {} \;
2) Or run the latest combo updater (rather than the delta), from https://support.apple.com/kb/DL1804?