if this is windows, you might try this: - rightclick on desktop - select New>Shortcut - browse to c:\program files\Mozilla thunderbird and select thunderbird.exe

 (if 32-bit, go to c:\program files (x86)\Mozilla thunderbird and select thunderbird.exe 

I think that will do it.

In Program Files(x86)/Mozilla Thunderbird are several .exe files, but no thunderbird.exe.

You use the 32-bit version? Can you post a screenshot of that folder? Have you also checked c:\program files to see if there is a mozilla thunderbird folder there?

Yes, I have the 32-bit version. No, there is no mozilla version in c:/program files. I post 2 screenshots of all the files in the Mozilla Thunderbird files.

Is there a Thunderbird exe in program files?

No, there is no Thunderbird exe in program files. Can I download one and put it there?

I put a Thunderbird exe in program files (I copied it from my new computer). But when I tried to open Thunderbird I get: "The aplication was unable to start correctly."

I suggest you reinstall on the PC. No idea why the exe is missing. For safety, I always backup the profile prior to that. Be sure to install the 32-bit version.

Thanks David and Matt, my e-mail workes again!