Find the Web Address (URL) of a File on Your Hosting

Files on your main domain

Log in to File Manager or FTP. Note the parent folder of your file. For your main domain this is normally public_html.
Open public_html. If the file is here, go to step 4. If it is in a subfolder, open each folder and write down the names. Folder and file names are case sensitive.
Note the full path, folder by folder.
Add the file name at the end of the path, exactly as it is written, with its capital letters.

Examples of paths:

public_html/My_Life.pdf
public_html/images/Image25x120.JPG
public_html/blog/includes/Movies/bigCow.avi

Replace public_html with https:// and your main domain name:

https://primarydomain.com/My_Life.pdf
https://primarydomain.com/images/Image25x120.JPG
https://primarydomain.com/blog/includes/Movies/bigCow.avi

Open the link in a browser to test it.

Files of an addon domain or subdomain

The folder of an addon domain or a subdomain is usually inside public_html or next to it, and has its own document root. Look at its document root in your control panel, for example in Domains in cPanel. Then use the same steps. Replace the document root with https:// and the addon domain:

public_html/addondomain.com/file.pdf  ->  https://addondomain.com/file.pdf

If the link does not work

Check the capital letters in the name.
Spaces in names become %20 in links. Rename files to avoid spaces.
Make sure the file is in the document root of the domain.
Check the file permissions (644 for files, 755 for folders).
Files outside public_html (your home folder, for example) cannot be reached from the web.

Quick recap

Write the path from public_html down to the file.
Replace public_html with https://yourdomain.com.
File names are case sensitive.