how to find an original file from an alias

Simply renaming the folder the file you need was in can't make it magically reappear. The only thing that will happen is the folder will have a new name.

If I'm assuming correctly, it sounds like there are multiple versions in a Time Machine backup of the file you're looking for. If the version you need is back further than TM can go, then it's gone.

The only other thing I can suggest is doing a deep search of every drive you own. EasyFind is great at this. You can download version 5 either directly from the vendor (my link), or from the App Store.

Set the left column options like this:

Type in the name of the file and hit return. It will search the startup drive first by default. Change the top drop down menu for each drive you want to search.

The Finder is too busy spewing error messages when the original item for the alias is not found, or has been deleted. The following AppleScript/Objective-C looks at the alias bundle to extract the original item's path, even if that last path location was in the Trash before it was subsequently deleted. This item was on the Desktop along with its alias before I moved the original to the Trash and emptied it:

use framework "Foundation"
use AppleScript version "2.4" -- Yosemite 10.10 or later
use scripting additions

property NSURL : a reference to current application's NSURL
property NSURLPathKey : a reference to current application's NSURLPathKey

set af to POSIX path of (choose file default location (path to desktop))

set aliasURL to NSURL's fileURLWithPath:af
set bookmarkData to NSURL's bookmarkDataWithContentsOfURL:aliasURL |error|:0
set bmvalue to NSURL's resourceValuesForKeys:[NSURLPathKey] fromBookmarkData:bookmarkData

display dialog ((bmvalue's objectForKey:"_NSURLPathKey")'s stringByAbbreviatingWithTildeInPath()) as text
return





Then the original has likely been deleted from the drive.

The aliases got bigger some versions of the Mac OS back because they're no longer simple, direct pointers. You can do things like rename the item the alias points to, and/or move it to another folder or drive, and the alias will still know where it is.

To lose track of the linked item completely, the original is likely missing. Or, it's on a removable drive that is currently not available.

If the alias isn't completely damaged, you can right click on it and choose Show Original.

I've been using EasyFind for years. It works just fine in High Sierra. The current version works all the way back to Yosemite, according to the vendor's site.