final cut x library

Hi,

I use final cut x and i recently installed extra ram on my imac and rebooted in 64 bit mode. Now all the files are gone from my library events folders - they are all empty except the short timeline I had been working. Do you know how I get them back? If I 'Import' it only asks to look for the relevant footage for the files that are on my time line. How do I reconnect? I read that the library in final cut x saves automatically as I could never see how to save my project, so I presume it must still be on my machine somewhere? When I installed my extra ram I had to disconnect the external drive I had my footage on but I've reconnected it now. Any ideas? My imac is late 2009 27 inch.

Mary