Please check that the calender in suitable for this version or not.

Hi MaryBThigpen, Thank you for your question, however there is no built in calendar in Firefox. If there is an add on that you were using you can check the profile folder to see if there is an instance of the data that would have been stored in it.

It may just be a matter of logging into the calendar add on one more time. What did you use?

The calendar was in Mozilla not Firefox. I downloaded as suggested in other responses to this post. It downloads w/an xpi extension. I have searched for a program to open that extension w/out luck. It would be great to get a calendar back but that doesn't help me retrieve ALL the events already set up on the calendar. I am at a loss to understand why Mozilla would xl the calendar. It was a VERY GOOD calendar. I can't believe I am the only one missing it.

Hi MaryBThigpen, I would like to confirm with you where the Mozilla is? There is a calendar add on called Lightning that can be added to Mozilla Thunderbird, the email client. Was there an email associated with the calendar, it may be on the service provider's website.

Xpi extentions are install packages that bundle an installation folder for a program for many operating systems More on XPI here if you are curious

I am hoping that this is not https://wiki.mozilla.org/Calendar:Deprecated:XPI_Support what you are affected by. As the support for xpi calendars managed by seamonkey has be depreciated. Is this the case?

Thank you to all who posted a response to my problem. I am not a novice computer user but neither am I an expert. I tried all the suggested fixes w/out success. I found another calender...tho' not nearly as good a calendar as the Thunderbird calender. I am abandoning Thunderbird altogether & will 'make do' w/the new calendar. Thank you again for trying to help me. MBT