Please, help me. I try to download APA 6th and “save as” in my End Note and OOOOOOHHHH, my library disappear.  And I cant install APA 6th. 

That is kinda weird.  Downloading the style should open in Endnote, and then from there you should just ask Endnote to save it from the File, save as.  Then you can access it from the Edit>edit output styles>open style manager, where you should see it.  How did you try to save it? 

There is no way any of that should affect your library?  It may just be a new “window” and if you look under the endnote’s  window menu, can you move to the library window (near the bottom of the menu?)  or try File open, in case it closed – or finally, make sure it hasn’t been minimized and sitting just at the bottom left of the endnote window - one way to find it might be to go to the endnote window menu and say “cascade”