Photo app not editing on iMac - nothing happens when I try to make adjustments or use the filters. Help, please!

Question

mid-2010 iMac, 4GB, running OS X Yosemite 10.10.3. Thing just seems frozen in Adjustments and Filters, but will Rotate, Crop and occasionally Straighten. Sometimes will Retouch, but not at all times. Any thoughts?

Answer 1

Create a second Photos library, just for testing. To create the test library, hold down the alt/options key while launching Photos. Import a few photos for testing. Can you add adjustments in a new library?
If yes, than you have probably a library corruption. Try to repair the Photos library., but make first a backup copy of the library.
To repair hold down the  alt/option and the command key simultaneously while double clicking the iPhotos application in the Applications folder  to launch the Photos Library First Aid tools. Hold down both keys firmly and long enough, until the First Aid panel will appear.  The select "Repair database". 
if no, and the new library does not any work better, the GUI items may not work because of corrupted Preferences files.
The Photos.app stores the preference settings in a file in your hidden User Library.  If this file has become corrupted, you can see all kinds of problems with the graphical user interface - missing menu items, etc.
To remove this file, do the following.
Quit Photos, if it is running.
Reveal your user library and delete this folder:  ~/Library/Containers/com.apple.Photos/
To reveal the hidden User Library:
Bring the Finder forward by clicking on the Desktop or the Finder icon in the Dock.
Select your user/home folder (with the house icon in the Finder sidebar)
With that Finder window as the front window, press the key combination ⌘J to bring up the View options.
In the View options panel enable ’Show Library Folder’. That will make your user library folder visible in your Home folder.
Open your Home folder, then the Library folder, then Containers.
Move the complete folder com.apple.Photos to your desktop. Move the entire folder, not just the contents.
Now restart the Mac and try again.  If all is well, delete the folder from the Desktop.
Be aware, that removing the Preferences will reset all preferences you set using the Preferences panel in Photos. You will have to set them again.  Also, Photos will not remember the location of your Photos library. If the library is not in the default location in your Pictures folder, you have to open it directly by double clicking it.