You have some malware. You'll need to go through all apps and uninstall anything potentially shady and check permissions as well. I'd also install avast antivirus or another reputable one that isn't an ad flooder of its own.

I should also mention some of the worst offenders of malware are all the custom theme's, custom ui's, keyboard and emoji layouts. Most common place to sneak in malware.

 

Huh! I went to the Samsung Shop in the mall a couple of days ago because I had a new 'message' on the home screen of my non-smart ($20) Samsung phone. Before I knew it, the guy there mumbled something and did a factory re-set. All messages (around 500, in and out, including some very important ones, gone. All contacts, gone...

 

No... your post asked if anyone'd (there's only me as the user) installed any apps recently. I've heaps of apps - mainly radio and news - but only Kindle was/is recent. And I'm about ver 4.4.

 

Thanks to all for your comments and suggestions. I installed a free version of Avast and the problem is completely cured.... Now, about hearing aids...