When you begin using the new Photos library it will migrate your current working iPhoto library to a new Photos library. You will end up with two library, one a Photos library and the other a migrated iPhoto library. They initially share the same space on the hard drive so don't take up twice the space as the iPhoto did initially.
You can still use iPhoto. iPhoto wasn't deleted from your hard drive. It was just removed from the Dock and is still in the Applications folder. In order to get iPhoto 9.6.1 from the App Store you first must have some version of iPhoto 9.X on your hard drive. If you do try following Terence Devlin's instructions in this post to obtain iPhoto 9.6.1 from the App Store:
Terence Devlin
Apr 14, 2015 11:21 AM
Re: Is Iphoto gone ? i want it back!
in response to Johannes666
Recommended
Go to the App Store and check out the Purchases List. If iPhoto is there then it will be v9.6.1
If iPhoto 9.6.1 is there, close the App Store, drag your existing iPhoto app (not the library, just the app) to the trash and then go back to the App Store.
Install the App from the App Store.
Sometimes iPhoto is not visible on the Purchases List. it may be hidden. See this article for details on how to unhide it.
http://support.apple.com/kb/HT4928
One question often asked: Will I lose my Photos if I reinstall?
iPhoto the application and the iPhoto Library are two different parts of the iPhoto programme. So, reinstalling the app should not affect the Library. BUT you should always have a back up before doing this kind of work. Always.
NOTE: the key to this procedure is to move the existing version of iPhoto 9 to the Trash bin in the Dock (don't empty yet) before going to the App Store.
