This Seeking Tech guide will explain how you can quickly redownload and reinstall deleted Starfield mods from the Creation Kit. In order to do so, you need to do the following:
1. Head back to the main menu if you are currently playing the game.
2. Go to creations from the main menu.
3. Open the Options menu. This can be done by pressing the Menu button on the Xbox controller.
4. Select Download all Creations in My Library.
5. Once the downloads have been completed, exit the Creations menu and then load back into your game.