OS X Yosemite looks great but has some strange bugs (See «How to fix the Notification Center on OS X Yosemite»). An other bug is the broken Finder search. I found this after I tried to search files in a unpacked folder of some downloaded files. They were inside the folder, but Finder just didn’t found them. Looks like Spotlight is broken on OS X Yosemite.
Finally I tried to reset Spotlight.
Open the Terminal application (Terminal @Spotlight – this should work!) and run these commands to reset Spotlight:
sudo rm -rf /.Spotlight-V100 sudo rm -rf /.Spotlight-V200 sudo mdutil -i off / sudo mdutil -i on / sudo mdutil -E /
The Finder search should work fine right now, but it could break again – just run the commands above again.
Alternatively you could download (or just create your own) the commands bundled to a bash script and run it directly:
wget http://marcel.zurreck.com/files/os_x_spotlight_reset.sh ./os_x_spotlight_reset.sh