Unity 16.04 accented letters don't show in dash, hud, and are replaced in window title bars

running 16.04 since its official release. Up to date. Since few days I have a problem with accented letters :

1. in dash if I type « démarrage » on keayboard I only get «dmarrage» in the dash,
2. same behavior in HUD,
3. in windows title bars accented letters are replaced with kind of squares.

For (3) letters are correct once window is maximised that is to say when title bar is in the top panel. I've found other discussion here about that, with neither explanation nor fix : Accented characters not rendering correctly on title bar in Ubuntu 14.04 or Weird "Box-like" Characters Showing up in Title Bar of Windows

Here you may find illustrations of my situation and what has been checked so far about locales and other language settings ( in french ) https://forum.ubuntu-fr.org/viewtopic.php?pid=21551698#p21551698

And last here is reported bug on Launchpad https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1599516

Any hint or help very welcome ;-) what may I check ?

Solved in both ubuntu 16.04 & 14.04 ;-)

Bleachbit most probably deleted too many files regarding localizations.

Thanks to that post I've managed to reinstall the missing packages.

More details on Launchpad, from comment #38 and following.

Helped by the command provided by bertrand0

dpkg-query -S \*/{translations,locale,locales,locale-langpack,i18n} | sed -r 's/, /\n/g' | sed -r 's/:.*//' | sort -u | sudo xargs aptitude reinstall

I've finally obtained a list of packages to reinstall. Beware manually installed .deb packages had to be removed from the list issued by the command.

It looked like this on my 16.04 :

sudo aptitude reinstall apt chromium-browser chromium-browser-l10n cups-common dconf-editor debconf-i18n dpkg e2fsprogs example-content firefox firefox-locale-fr fwupdate gimp-data gimp-plugin-registry gksu gnome-icon-theme gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly iso-codes language-pack-fr language-pack-fr-base language-pack-gnome-fr language-pack-gnome-fr-base language-selector-common libapt-inst2.0 libapt-pkg5.0 libc-bin libgimp2.0 libgksu2-0 libgom-1.0-common liboxideqtcore0 libqt4-script libstdc++-5-dev libx11-data libzvbi-common locales menu pavucontrol qtcore4-l10n qttranslations5-l10n radiotray synaptic unity-lens-applications unity-lens-files unity-tweak-tool update-notifier-common vlc-data xdg-user-dirs xkb-data-i18n xscreensaver