To reset the link between iTunes and your library:
Click the iTunes menu on the Mac or Edit menu on the PC
Click Preferences
Click the Advanced tab
Click the Change button in the iTunes Media folder location section
Browse your computer and locate your external hard drive
Browse to determine your iTunes Media folder and select it
Double click on it or click Open .
Click OK in the Preferences window.
When done, the iTunes program will know where to find music files and you can listen to music as usual.
How to prevent the error 'The Original File Could Not Be Found Error' in the future?
Do you want to prevent this problem from happening? You can do this by changing a setting in iTunes. Here are the steps:
Open iTunes
Click the iTunes menu on the Mac or Edit menu on the PC.
Click Preferences
In the pop-up window, click the Advanced tab
Select Keep iTunes Media folder organized
Click OK .
By enabling this setting, each time you add new songs to iTunes, the song will automatically be added to the correct location in your iTunes Music folder, regardless of where the file was located before.
This will not fix any songs with errors 'the original file could not be found', but will prevent this error from happening in the future.
See more:
Fix PC error not receiving iPhone in iTunes
How to fix iPhone music sync problems with iTunes when updating iOS 11
Does iTunes not work on Windows 10? This is how to fix it