How can I switch languages like in Windows with Alt+Shift(L or R) or in any of Alt+Shift?
I make it work to get the next languages but it didn't get back to main language without using Shift+L OR Alt+L.
Ubuntu 12.04 LTS
I'll assume you have added a second (or more) keyboard layouts. If so, a keyboard indicator will appear on the top of your screen.
If you click on it, a menu will appear; go to the last option, Keyboard layout configuration.... You'll see the same settings window from where you added the additional layout(s):
Click on the Options... button on the lower right corner.
On the "Keyboard layout options" window, navigate down to Key(s) to change layout, click on it and select the combination of keys that better suit you.
Note: please keep in mind that my system is in Spanish, so the actual phrasing or words of the options, menus or applications might be somewhat different from what I've written in English. Feel free to correct (me or the post directly).