Thanks Blossom. I don't believe it was Amazon servers because a download from the store worked perfectly on another KF. I think it was data that was the problem. I did the gear thing up top, plus more button and entered the applications area. Here I used ALL APPS, (not just running), found the store app and cleared the cache and the data. Got warnings, but went ahead. It seems to have fixed the problem.
I had uninstalled several apps I had recently downloaded in case one of them might have been the culprit and then couldn't re-install them either. Was about ready to do a hard reset, but glad I persevered. Seems all is well now. Thanks for all the suggestions.