GParted not working error while loading shared libraries: libgtkmm-2.4.so.1

Try removing these packages gparted libatkmm-1.6-1v5 libgtkmm-2.4-1v5 libgtkmm-3.0-1v5 pavucontrol type in this command.

sudo apt-get remove gparted libatkmm-1.6-1v5 libgtkmm-2.4-1v5 libgtkmm-3.0-1v5 pavucontrol 

and then install ubuntu-desktop if it removes it.

sudo apt-get install ubuntu-desktop gparted libatkmm-1.6-1v5 libgtkmm-2.4-1v5 libgtkmm-3.0-1v5 pavucontrol

Just after Bionic's fresh install, the missing libraries used by GParted can be installed with:

sudo apt-get install --reinstall libgtkmm-2.4-1v5 libatkmm-1.6-1v5 libpangomm-1.4-1v5 libglibmm-2.4-1v5 libsigc++-2.0-0v5 libcairomm-1.0-1v5

This command worked for me

sudo apt install --reinstall libgtkmm-2.4-1v5