Downloads live in where you downloaded them, so if you saved them to Downloads, they are there, Desktop, etc. Firefox doesn't store your downloads.

Thanks Tyler, however, I can't find them anywhere in any of the files  :(

You can copy the downloads.sqlite file from the Old Firefox Data folder on the desktop to the current Firefox profile folder.

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder