What should I do if the weather forecast on the original wallpaper of Samsung s6edge is lost?

According to your description, I suggest you operate: Settings-Personal-Wallpaper-Home Screen/Lock Screen/Home Screen and Lock Screen-Real-time Weather.

You can also add weather gadgets to your mobile phone screen. How to do it: Press and hold a blank position on the standby desktop-select the weather widget at the bottom of the screen.