How do I uninstall the new Photos app and go back to iPhoto? The new upgrade is not allowing me to see any of my over 16000 other pictures I had in iPhoto.

You cannot uninstall Photos, it is installed a part of the System, but you can simply remove the icon from the Dock and ignore Photos. It is not compulsory to use it. Just continue to use iPhoto, if you prefer it.

If you did not uninstall iPhoto, it will still be in your Applications folder. Drag iPhoto from Applications to the Dock, then click it to launch. When you launch iPhoto again you will see a warning, that the library has been migrated to Photos. Click the "Open iPhoto" button in this panel.

With Yosemite you need if version 9.6.1. If you did not yet update to this version, the iPhoto icon will be crossed out. In that case update to version 9.6.1.

if you missed the update: You can no longer buy iPhoto from the App Store anywhere, and also not update it from the "Updates" tab of the App Store. You can however reinstall it, if it is showing among your Purchases at the App Store and associated with your AppleID.

Sign into the App Store and look at the Purchases tab.

Reinstall as described in this User Tip:

Get iPhoto 9.6.1 if you didn't update before OS... | Apple Support Communities

The main idea is to move the incompatible iPhoto app to the Trash, so Spotlight does not see it as installed, reload the App Store by pressing ⌘R, and then to try to download again from the App Store - from your Purchases tab, not from the main page, since you can neither buy iPhoto nor update it, but you can reinstall, if your AppleID is associated with it.

So move iPhoto to the Trash (don't empty the Trash), relaunch the App Store. The button to the right if iPhoto should change to Install on the "Purchases" tab.

If you do not see iPhoto there, try to unhide your Purchases as described on this page: Hide and unhide purchases in the Mac App Store - Apple Support

You're welcome. 🙂

You may want to let the Apple developer team know which features you are considering essential in a Photos.app. You could use the feedback form to send a feature request:

Apple - Photos - Feedback

Tell me about it, I found is so frustrating that the new app would be less helpful than the old one, Why would they make an update where we can't see all of our photos and only a select few? When I first opened this app I had a mini heart attack thinking I had lost everything.

Why would they make an update where we can't see all of our photos and only a select few? When I first opened this app I had a mini heart attack thinking I had lost everything.

Photos is not an update. It is a completely different new application and you are currently seeing the very first version. It will need time to develop into a full fledged application. It has been completely designed new, from scratch, using only the new libraries from Yosemite for more efficiency and faster performance.It has more advanced editing options than iPhoto. And it supports iCloud Photo lIbrary for a better integration of the photos on mobile devices. The next version of Photos will already have more features, as announced by Apple, and I hope with time the application will be better than iPhoto.

You don't have to use the new baby app now; iPhoto is still working. So wait and see what will become of Photos.

Thank you for your response Leonie. My question is also where has my folder of photos gone to, I would like to back it up on my external hard drive and I can no longer find it. I used to just be able to drag and drop the folder into the hard-drive and now it is gone. I can see that I can continue to use iPhoto (big relief) however where are these photos now being stored? Again thank you for your quick help.

My question is also where has my folder of photos gone to, I would like to back it up on my external hard drive and I can no longer find it.

Please start a new discussion with this question.

Then tell us, which version of iPhoto you upgraded from and where you used to keep the iphoto Library. By default tt should be in your Pictures folder and called "iPhoto Library.photolibrary". The migration may have renamed it to "iPhoto Library.migratedphotolibrary", but it will still be an iPhoto Library and you can open it in iPhoto.