I would like to know why I can't get the terminals
tty2 etc while pressing Ctrl-Alt-(F1 ,F2) etc.I don't know why I can't get these terminals.Is it because my laptop is Toshiba Satellite C55-B5270?
As many laptops uses the function keys to adjust screen brightness, speaker volume and things like that, they often have a Fn key that you would also have to press to get plain function key behaviour.
Judging from photos of the Toshiba Satellite C55-B5270 keyboard on the net, this key is located to the right of the left Ctrl key.
There might also be a FnLk ("function lock") key, or similar, that you can toggle this behaviour with so that you don't have to press Fn every time.