If you already have the language installed … all you need to do is add the “Keyboard Layout Switcher” panel applet to the bottom panel.
Right-click the bottom panel, and select Add / Remove Panel Items … Click the + Add button … highlight the Keyboard Layout Switcher and click the + Add button.
Now before you close the next window … have a look at your bottom panel, the keyboard switcher will be there by your clock … if you want to move it, use the Up and Down buttons.
To use the Switcher … just normal (left) click the icon on the panel and it should switch.
If it doesn’t … open a terminal (Ctrl+Alt+T), run this:
gedit /etc/default/keyboard
and post the contents of that file here.
I dunno if it will do the Alt+Shift keyboard shortcut … but maybe we can add that keyboard shortcut later if you really want it.
[EDIT]
OK, to add the Alt+Shift keyboard shortcut to toggle between Russian (ru) and UK English (gb) keyboards … you need to add the line:-
@setxkbmap -option grp:alt_shift_toggle “gb,ru”
to the file:-
/etc/xdg/lxsession/Peppermint/autostart
Then log off and on again (or reboot) for the changes to be applied.
Here’s a single command to add that:
echo '@setxkbmap -option grp:alt_shift_toggle "gb,ru"' | sudo tee -a /etc/xdg/lxsession/Peppermint/autostart
now log off/on.
If you have the Keyboard Layout Switcher panel applet installed … you’ll also see the flag change.
Reference source (needs modifying as above for Peppermint):
https://help.ubuntu.com/community/Lubuntu/Keyboard
.