KBees37 You can try recovering a backup version of this save. The game keeps the data from the last five times you saved before the most recent one, and these are all usable saves when renamed. Here's how to recover them manually:
https://sims4.crinrict.com/eng/2014/09/recover-backup-save-game/
The Tray folder contains saved households and builds, but it doesn't place them in your new saves. They're just available in your in-game library. Were they not present there after you moved over the folder? If so, please make sure the individual files are all directly in ...The Sims 4 > Tray, not in a subfolder.