My trash icon disappeared from my desktop

Perhaps you tried superhuman effort to empty the trash, or inadvertently some command-

line; as this issue is rare, yet has a history from older Mac OS X to later versions macOS.

Early attempts to cure this issue, starts from search online; I recollect this kind of effort:

"..(had bother) you to reset your Dock? Go to ~/Library/Preferences, and remove

com.apple.dock.plist. Restart. ~ If this fails, put the preference back .."

"..think you should first use killall Dock using Terminal." (another go at it)

"You shouldn't be able to delete the Trash folder from your Dock.

To put it back, reset your Dock settings:

1. Open Terminal (/Applications/Utilities/Terminal.app)
2. Run the following command to delete the Dock preferences file:
3. rm ~/Library/Preferences/com.apple.dock.plist
4. Log out and back in."

{As times and code has changed from early Mac OS X Leopard/Tiger, paths

which worked a few decades ago might be a bit dusty by this late a date.}

Start up your Mac in safe mode - Apple Support (something to try now?)

Use safe mode on your Mac - Apple Support

//support.apple.com/en-us/HT201262

Your system Help files should be helpful in modern versions macOS

well past Catalina 10.15.7 where systems are much more protected..

From recent help views (beyond my macOS 10.13.6) well into post 10.15.7:

If the icon isn’t in the Dock, there are other ways to open the app on your Mac:

• Click the Launchpad icon in the Dock, then click an app icon. See Use Launchpad to view and open apps.
• Use Siri to open an app for you. Say something like “Open Calculator.” See Use Siri.
• Click Spotlight in the menu bar, enter an app’s name in the search field, then press Return. See Search with Spotlight.
• If you recently used an app, choose Apple menu > Recent Items, then choose the app.
• Click the Finder icon in the Dock, click Applications in the sidebar of the Finder window, then double-click the app.

..

A search (duckduckgo) with browser should show many choice results; some are older.

Good luck in this matter, and place a few cautionary signs ahead if you travel here again.