>>> Do I need to 'find' the download TD <<<
No .....it is a temp file which is either used or abandoned.
Download it as described above.......leave the PC alone to do it's thing and until Opera re-opens with a splash screen ( on a new tab) indicating that the new is installed.
However, from what you say you have half an update, but no it will not "twiddle" itself on reboot.........so go to
http://www.filehippo.com/download_opera/ and hit the green "download latest version" button ( top right hand corner ) and save that to your desktop.
Once you have that......control panel/add remove progs and uninstall current version then fresh install from the downloaded one.
Don't worry...your prefs. will be safe.