I dont seem to have iPhoto on my Mac and can't find a link to download it, only to update it.
Here is the download link of iPhoto 9.4.3
Other versions here:
- Install iLife '11 (or some other version of your choosing that's compatible) from an iLife disk. You'll need to purchase it from somewhere like Amazon or possibly Apple if you somehow manage to get them to agree to send you one from there deep depths (by calling their support or something)–however, once you do so, it's easy riding.
- Though I haven't tried it myself, apparently the iPhoto 9.2.3 update actually contains a full version of iPhoto that you can extract using something like Pacifist.
- Find a "friend" who happens to have a copy of the relevant installer/application lying around.
There is no way to legally download the latest version of iPhoto for free, as it only came 'free' with brand new Macs for a few years (and has now been replaced on the newest Macs with an app just called "Photos"). With the new Macs that qualified for the free downloads, the first time you signed in to the App Store you would be prompted to "Accept" iPhoto, iMovie and Garageband which would then bind these apps to your Apple ID as purchases (although they were free). At this point you could then technically download them on all machines that you owned for free, provided they met system requirements and you remembered your Apple ID and password (no activation key required).
If you're running Mac OS X 10.6.8 though, Apple outlines that only iPhoto 9.2.3 or lower is compatible, which is not available on the App Store.
If you could locate your original discs that came with your Mac, you could reinstall iPhoto from the second disc titled "Applications Install DVD". If your Mac came with an older OS than Snow Leopard and you upgraded after the fact it may not have included these applications to begin with (depending on how old).
You could try calling Apple. As of 2 years ago I know they were still able to replace this disc for you with an original for $15 upon request.
I am curious though... if you have a button that says "Update" and not "Download", barring any other weird glitches that usually means that the App Store is seeing the "iPhoto.app" SOMEWHERE on your hard drive. Have you tried running a search to see if maybe it just accidentally got moved/dragged somewhere other than the Applications folder? (Like the Trash or another user's Desktop?)