Hello! my landscape is showing up black

Here is the problem. I uploaded my imported asset folder onto my flash drive. Unknowingly, I forgot to put the landscape mat material within the imported asset folder as well. When I got to school, the material did not show, since there was no landscape material mat found. I continued to work on the project some more at school, but when I made it home, I deleted the previous version. Now, I copied the previous material mat version, and put it into my imported asset folder. When I apply it to my current map, it shows up black? Note: I’m still quite new to this program.

Perhaps try adding a light source, a directional light source or whatever.