I installed LTS 14.04 and ever since some of my keys went missing. First, the dot symbol key is not working, so I have to use the dot key from the numeric keypad. Secondly, the right alt key is a shortcut for mute speaker volume although I deleted all multi media short cuts in the system settings/keyboard. Thirdly, on the 12.04 LTS version and with english language option selected I was able to type german characters while pressing the right Alt key + q,y,p for ä,ü,ö. This was very convenient, because I did not have to switch to German language. This feature does not work any longer, because the right Alt key is now mute speaker volume and I can't change it. I appreciate your help and thank you.
Assuming you are talking about English (US, international with dead keys), that keyboard layout turns the quotation symbol key to a dead_diaeresis key for typing e.g. ë. To type the quotation symbol you need to press both
The dot key should be unchanged, though.
You can see an overview of the currently selected keyboard layout by clicking the input source indicator in the menu and selecting Keyboard Layout Chart.