Sounds like the download failed. Why did it take days?

http://kb.mozillazine.org/Issues_with_Firefox#Downloading_opening_or_saving_files

This download manager works separately from the browser. The browser tells it what to download, and off it goes.

http://www.freedownloadmanager.org It is a powerful modern download accelerator and organizer for Windows and Mac.

The internet connection is very slow. So I'll have to over again?

Sometimes the download can be restarted from where it left off. Sometimes it starts from the beginning.

Give the downloader I posted a try.

When you have a slow connection or otherwise experience connection issues then best is always to use an external download manager.

Also make sure that your security software isn't interfering and possibly removes downloads.

You can check the 162 bytes file in a text editor to see if it contains an error message.

There is no resume or retry button because it is a "completed" download. I don't know why Firefox would say completed when it failed. And I can't find the .part file. The 162 byte file says 403 Forbidden. When I paste the link into the download manager, it also gives the 403 error. So I guess the link is broken? Anyway, thanks for replying

Open the browser for the link. Then call the manager.

Delete the old file first.