LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
... the symbols on the LCD have black colour. If I don't use this line, they have white colour. Without the lcd.begin() line I I still can't display some letters. Why does the lcd.begin changes the text colour from white to black? White is much more visible on blue backlight. Is there a way to avoid it?
As far as your other problem goes - you appear to be having trouble with your LCD DB7 line (pin 14), it is always low. This may be a problem with your soldering or with your breadboard.Don