Hey there, sorry to hear you've been stuck with this missing menu issue for days—let's break down some actionable steps to get that Kit Tools menu showing up again.

Basic Import & Compatibility Checks #

• Double-check the asset's import status
  Head to Window > Package Manager, switch to the In Project tab, and locate 3D Tool Kit. If it shows a partial import or failed status, click Reimport to refresh it. If that doesn't work, consider deleting the asset entirely from your project (back up first!) and re-downloading it from the Asset Store—sometimes partial imports can break editor features.
• Confirm version compatibility
  Unity 2019.1 is an older release, so make sure the version of 3D Tool Kit you downloaded explicitly supports it. Check the asset's page on the Asset Store for compatibility notes—if it's built for newer Unity versions, you might need to either upgrade your Unity editor (if your project allows) or find an older version of the toolkit that works with 2019.1.

Menu Refresh & Layout Fixes #

• Force Unity to refresh editor menus
  Unity doesn't always pick up new editor scripts right away. Try these steps:
  • Hit Assets > Refresh (or use the shortcut Ctrl+R/Cmd+R)
  • Close and fully restart the Unity editor—this clears temporary editor cache that might be blocking the menu
  • Clear Unity's global cache: Go to Edit > Preferences > Cache Server, click Clear Cache, then restart Unity
• Reset your editor layout
  Sometimes a wonky layout can hide menus without you noticing. Go to Window > Layouts > Reset to Factory Settings—this will restore the default editor setup, and your Kit Tools menu might reappear.

Editor Script & Compilation Checks #

• Verify editor script placement
  The Kit Tools menu is powered by editor scripts, which Unity only recognizes if they're inside an Editor folder. Search your project for scripts related to Kit Tools (look for names like KitToolsMenu or similar) and make sure they're stored in a folder named Editor (subfolders inside Editor are okay too). If they're in the wrong place, move them and refresh assets.
• Check for console errors
  Open Window > General > Console and look for any compilation errors linked to 3D Tool Kit. If there are errors (like missing dependencies, syntax issues, or conflicts with other assets), the editor scripts won't run—and the menu won't show up. Fixing these errors is critical; common culprits are conflicting assets or outdated script syntax that doesn't work with Unity 2019.1.

Last Resort: Full Reinstall #

If none of the above works, do a clean reinstall:

1. Delete all 3D Tool Kit-related files from your project (check both the Assets folder and Packages manifest if it's a package-based import)
2. Restart Unity to ensure no residual data is left
3. Re-download and re-import the asset from the Asset Store

内容的提问来源于stack exchange，提问作者asciidude