External iphoto library issues

Hi. A few days ago I upgraded to 10.10.5 plus other 3 updates, the thing is that before that, I had an iPhoto library copy in an external hard drive named "iPhoto Library_2" but now, after the updates I can't open it, showing an advertisment "unreadable files: 2", "The files have an unknown format" and then it keeps opening my computer iPhoto library "iPhoto Library", besides now the extension is shown in the external hard drive "iPhoto Library_2.photolibrary" . I'm afraid I lost all my pictures. i've tried opening the new app photos + option but doesn't work.