Cannot open attachments

[xsteamer]

I installed Thunderbird 55.0a1 on top of an old Thunderbird email program and it started not responding and now I cannot view attachments So I thought I would do a clean install of Thunderbird but first needed to save files and folders. So,I downloaded the import/export add on for Thunderbird. When I went to download it, it asked what app would I like to use with it so I picked Adobe Acrobat Reader because I have loaded on the PC. Well it was an .xpi file which Adobe converted to a .pdf file and Adobe cannot open xpi files. I downloaded the add on again and it was downloaded as a .pdf file.
1) How do I convert it back to an .xpi file?
2) How can I prevent future downloads being downloaded as .pdf files?
3) How can I view email attachments, i.e. mp4's, jpg's mov. et?

[DanRaisch]

1) Don't convert anything, just delete the problem file and download a new copy, referring to the following.
Right click the download link on the extension's home page and choose "Save Link As...". Then, in Thunderbird, go to Tools->Addons->Extensions tab->click on the "Gear" icon and select "Install Add-on from File" from the drop down list. Navigate to the just downloaded .xpi file and select it. Click on the "Open" button. The installation will now begin. You will need to close and reopen Thunderbird to complete the install.

2/3) See this article -- http://kb.mozillazine.org/Actions_for_a ... file_types

[xsteamer]

I still cannot open attachments

[DanRaisch]

Based on the information I posted above, what have you done to correct this issue?

[BruceAWittmeier]

Do your attachments have a file extension to identify the program that should be used to open the attachments? Can you save the attachments, then open them separately by double clicking the file directly?