Hello there pollock3. Addres book is missing after starting up pc and software. Can you toggle the sidebar? By clicking on f9 in a new text message. Going to the main window layout and go to view>layout>and ensure that the directory pane or contact sidebar is checked Costimize the toolbar: right click the toolbar and select costumize and try to drag the adres book back on place. Or Click on that restore button.🎅 Why thunderbird does not showing you that wanted address book? And it is missing now? It s because of that stronger anti virus on the desktop did quarantine the files that we’re supposed to be used for that search of that address book that moment..to show it but it ain't there. After bad update s or crash or power losses thunderbird does not recognise these files anymore and has them as no good or missing files now. The wanted files to show you re address book are missing or were renamed at thunderbird and the search to use this files did not accept them for good files and they marked them as missing. Drag and drop functions can be having errors there to at this moment. The Version s 115 and 145 of thunderbird do show that or these symptoms continuously. Try to use the latest versions and rollbacks are possible to install to then use a version before that version and maybe a version before that could do the trick.. https://www.thunderbird.net/en-US/thunderbird/releases/ Greetings googlethunderbird.