Hey there, RoseM63NJ! Sorry to hear that. You can try performing a hard reset on the device to bring it back to factory defaults. You can do so by going to Settings > Backup & Reset > Factory data reset.
You can also try checking for software updates by going to Settings > Systems Updates, as your device may need an update to enable the option.
Hey there, RoseM63NJ! By default the Wi-Fi Hotspot option will show on the Settings menu. It can also be shown as Wi-Fi tethering.
We understand. In that case you can also try the hard reset, bringing the phone back to factory defaults. It would be just as it was when it was taken out of the box. You can do so by going to Settings > Backup & Reset > Factory data reset. Keep in mind that this also means that all of the contacts and apps will also be deleted from the phone, and you would need to authenticate the Google account that you have attached to it in order to regain access to the phone.