what reply?

There are several possible causes. Start by reading here: http://kb.mozillazine.org/Disappearing_mail

I really cannot follow the instructions on Disappearing Email or Recovering a Missing Profile. I'm 68 years old and am not that Computer or Program Sauvey. Could you have some one call me and walk me through so that I can get my email back to what I'm used to seeing on my PC? I would greatly appreciate it. I am frustrated and need my previously saved email folders and emails.

I can't offer to call you. I'm just a Thunderbird user like yourself, and judging by the time when you posted your message I'm halfway round the world away from you. (I'm also the same age as yourself and I don't have a computer background either, if that matters.) I appreciate that the 'disappearing mail' article appears rather daunting and I'll try to offer simpler instructions. However there are several possible causes for the symptoms you report and I can't guarantee to be able to solve your problem. In what follows I assume that your computer uses the Windows operating system. Go to your Windows start button and look through 'all programs': do you have a shortcut listed for the Thunderbird Profile Manager? If so, leave Thunderbird closed and click the shortcut to start the Profile Manager. Click on the 'create profile' button. In the window that appears, enter a descriptive name for the profile you want to recover. Then click the 'choose folder' button. If all goes well, at this stage you will see a folder named like 'xxxxxxxx.default' where the x's are a random string of eight letters and numbers. Click on this folder to select it and then press 'finish'. You should then see that profile in the profile manager window and you can start Thunderbird. Hopefully, your folders, settings and emails will have been restored.