Google OK apparently just spontaneously disappeared from my S5. It worked great for the first few days and then today it's no longer there. I've checked the Google Settings app and Hotword detection is set to On. I've tried toggling it back and forth, but it hasn't fixed the problem. Language is Default - US English.
I had this problem also. The ok google search box was gone on my Samsung Galaxy S5. It did not come as a result of deleting the widget. It was a completely spontaneous act.
The widget was gone, the app is still there, however I could not re enable it. There was no widget to simply long press and replace. Resetting the apps did not help. Clearing data did not help.
For me, this is what fixed it. In this order! I had failings when the order or steps were different.
Step 1 - Restart the phone.
Step 2 - Go into the Google App then into its settings then Voice
Step 3 - Go into OK Google detection.
Step 4 - Turn OFF From the Google App.
Step 5 - Exit out to the home screen them Restart your phone.
Step 6 - get back to the step 4. Then turn it back on & turn on From any screen.
Step 7 - You will be prompted to retrain voice model. Do this!
Step 8 - Turn OFF From any screen.
Step 9 - exit back to home screen.
Step 10 - Long press and go into widgets.
Step 11 - Under Launcher3 you will see small right arrow like this > Tap it.
Step 12 - You will see Launcher3 4 x 1 Google with the mic
Step 13 - Long press and drag it to your desired screen.
Why did this happen? I have no idea. It was spontaneous, I am 100% certain. Zero grey area.
I'm an optus customer in Australia. Phone came with plan.
Cheers to all!