after upgrading to 7.6.6, you need to re-install your plugins using the built in plugins > plugins admin.

for example: the side panel for ftp comes from the NppFTP plugin.
and the code shortcuts can eventually be from the plugin Snippets

best regards

side panel enabled

Did the panel show ALL the time, or only when selected via the tabs at the top?

If this contained a multitude of information, such as what I’d call a scratch pad, then likely it was just another file you had open in Notepad ++ (NPP) during the session. If you had enabled “Remember current session for next launch” and also “Enable session snapshot and periodic backup” (under Settings, Preferences, Backup) this allows for that scratch pad to be backed up and included on next launch of NPP.

Just below these settings is the location of the backup path, which may provide you with a file that contains the data you seek. Of course with the upgrading, some settings might have changed or been reset, so looking here might not help.
In my case the location is “C:\Users\USER ID HERE\AppData\Roaming\Notepad++\backup”, note the USER ID HERE which must be your account.

If you do find it, then I’d strongly suggest giving it a real filename, that way forcing it to exist as a file in a predetermined location, rather than as a temporary file only supported by the backup settings. The temporary files are generally named “new 1”, “new 2” etc. The backup version might have additional text in the filename stating a time period (of the backup).

Terry