Thunderbird won't load

I had Thunderbird installed on my Windows 10 computer and on my Android tablet. I noticed that some emails were not going. After hours reading posts on the internet I changed from POP3 to IMAP. Now nothing works. I uninstalled Thunderbird from both my laptop and the tablet and then did a download and reinstall on each. In each case I could receive email but now could not send. In the end I am uninstalled from both devices and loaded another product called EMclient. It installed instantly and properly on both the laptop and the tablet. I would like to return to Thunderbird, in spite of the fact that I lost a lot of emails in folders from a number of years of using the product, but would certainly like a lot simpler installation than what I experienced. Mozilla needs to look at other products and determine why they install so easily and Thunderbird is so difficult. I can't provide the version of Thunderbird other than the version for the laptop was the latest from mozilla's website and the version for the tablet was downloaded from the Play store in both cases this evening.