Try Open the Download Manager, click on the file with right button mouse and click on Open containing folder

• Download Manager

You still try do other download, when the firefox ask you to select where you want to save the file it will show the last place where was saved the last file, if the lost file was the last download probably you see it there

If the problems is with Yahoo! mail attachments, the download might actually never be reaching your computer. Users who are using an older bookmark to access Yahoo! mail have reported this problem. Try accessing your mail using one of these:

• Yahoo home page: https://www.yahoo.com/
• My Yahoo page: https://my.yahoo.com/
• Generic mail redirect: https://mail.yahoo.com/

Make sure to bookmark the new address if it works.

Some users have reported success with a different workaround, which is to go into Yahoo mail settings and switch to Basic mode.

Thanks, Old bookmark was the problem. Nothing would show in the download manager. There is no indication that the attachment doesn't download, but it is obvious now that it was just not downloading. Clue was the download manager arrow would not light up to green, indicating nothing being downloaded. Changed bookmark and now OK.