Help Saved Landscape Seems to be Missing?

Hi, new to Unreal. I created a terrain in Unreal then sculpted it and added a material. I thought I saved all Materials and assets but when I reopened Unreal the file just shows the default plane? Anyone know if I can recover the file or maybe I saved everything (I’m sure I did) but just don’t know how to open it or drag it to the stage. Anyways if someone could please advise on how to open the landscape I saved and how to properly save it for the next time. I would really appreciate it!

Thanks
Lorne