In OS X 10.10.2 the Finder's Preview function is not working In OS X 10.10.2 the Finder's Preview function is not working. If I select some image or pdf files I cannot see file's preview and only see wait logo. How can I fix these error?

I found some solution about qlmanage. Fixing Quick Look issues in OS X This can clear and rebuild the thumbnail's caches, however this program hung and did not finish.
From: Easy fix for Mac Finder preview thumnails not displaying

Delete all from your home &gt; library &gt; preferences. Delete all: com.apple.finder.plist

Proceed with logout and then login again.

Tried it, it should work!