How to restore the download button

What you’re seeing is probably not a damaged toolbar configuration at all. In Safari 26, the Downloads button is tied to the state of Safari’s download-history store.... when that list becomes empty, Safari removes the Downloads toolbar item rather than leaving a permanently available button, which is why it can also disappear from Customize Toolbar.

The first thing I’d check is Safari > Settings > General > Remove download list items.... if it’s set to something like After one day, Safari will periodically purge the history and the button disappears again. Set that to Never if you want the button to remain available, then download a small file once to repopulate the list. Option-Command-L is also the direct way to invoke the Downloads view, but it doesn’t change this underlying toolbar behavior. This is Safari’s intended UI logic in macOS 26, not a Finder or toolbar-preference problem.

If you mean the Downloads button in Safari’s toolbar on your MacBook Air running macOS 26.6, there are two possibilities.

First, open Safari, then choose View >> Customize Toolbar….

If Downloads appears among the available toolbar buttons, drag it back onto the toolbar and click Done.

Apple documents this as the way to add or remove Safari toolbar buttons in macOS 26. (Apple Support)

If you mean the Downloads button in Safari’s toolbar on your MacBook Air running macOS 26.6, there are two possibilities.

First, open Safari, then choose View → Customize Toolbar…. If Downloads appears among the available toolbar buttons, drag it back onto the toolbar and click Done. Apple documents this as the way to add or remove Safari toolbar buttons in macOS 26. (Apple Support)

However, there is an important detail: Safari normally hides the Downloads button when the download list is empty.Apple specifically notes that the button isn't shown when there are no items in the download list. (Apple Support)

So, if Downloads is not available in Customize Toolbar, download a small file first. The Downloads button should then appear near the upper-right of the Safari window.

If your goal is to make the Downloads button remain visible even after you have cleared the download list, tell us —that requires a different setting in Safari 26.6.

There are multiple 'Downloads' on macOS.

Restore the Download Icon in Safari

• Safari automatically hides the download progress icon when the download list is cleared or after a set time.
• To show active downloads manually, press Option + Command + L or go to View > Show Downloads while in Safari.
• If you meant a specific browser download button (like Chrome or Firefox) instead of Safari, please indicate the browser you are using.

Restore Downloads to the Dock

• Open Finder.
• Click Go > Home (or press Shift + Command + H).
• Find the Downloads folder.
• Drag the Downloads folder to the right side of the divider line on the Dock.
• Right-click (or control-click) the icon in the Dock to change how it displays (such as Fan or Grid)

More info: Use the Dock on Mac - Apple Support

Restore Downloads to the Finder Sidebar

• Open Finder.
• Click Finder > Settings (or Preferences) in the top menu bar.
• Select the Sidebar tab.
• Check the box next to Downloads under the Favorites section.

More info: Customise the Finder sidebar on Mac - Apple Support

To where? IN what app?