Post pages are missing

I no longer have a Front page or Home page with posts. I can only view my posts through sidebar widgets or an Archives page.

Selecting Settings>Readings>Front page displays>Your latest posts = a "Not Found Sorry, but you are looking for something that isn't here." message displaying on the home/front page.

I would greatly appreciate it if someone could help with this. I've been trying to fix it for almost two weeks now.

Many thanks to anyone willing to look into this,

SavvyBaker