You open the drafts folder and double click the message you want to send or continue to edit. This opens the draft message in the Composition window. The only window you can edit or send from. Does this not work for you and all the other Thunderbird users you represent?

The advice given to my request for help is the same advice that does not work and caused me to write for help. This is discouraging. It is possible that the frequent "updates" that Mozilla Thunderbird sends are the cause of the problem, to wit: these "upgrades" are essentially band-aids being put on top of band-aids to temporarily resolve problems that never get solved and fixed. Eventually, the program crumbles, and prior advice, such as that being given in response to my request, simply stopped working after one of the many updates being published created a new problem. Ah, progress by engineers!

Since you did not bother to say what you tried and did not work I told you how the program works. Maybe provide some details of your issue next time.