Previously the grass height was working and looked great. I turned my computer off, and a couple days later tried to render some more and suddenly the grass no longer renders.
Any help would be appreciated!
I’m sorry to hear about that @lola_2 !
In the very first instance just to make sure, please check if you have Grass/Carpet rendering enabled in the first place:
If so, please also check your Material settings and kindly send me a screenshot of the settings themselves as well. 
Thanks a lot in advance!