Ok, got it.
The keyboard apk may not have been touched, but it lost the voice recognition (mic) button when some other apk was removed. A long press on the A/ button just to the left of the spacebar (variously labeled T/, A/ or 1/, the / being a picture of the s-pen) pops up a few choices, one of which is the keyboard, but not the mic which is the default in the stock keyboard. Also, pulling out the s-pen while in a text composing screen automatically changes the keyboard to text recognition mode, but putting it back doesn't reverse the process. You need to long press that A/ button and select the keyboard icon.
Also, to do voice to text texting, for instance, you need to load the Skype apk and switch to that keyboard, or install Touchpal which also works. I installed the s-voice apk back in to see if that did it, but that's not the missing apk. As either the swype keyboard or the touchpal keyboard is perfectly fine for me, I'm probably not going to hunt for the apk that would 'fix' the samsung keyboard, but if anyone finds it, please let me know.
Thanks.