So I just upgraded to Ubuntu 18.04 from 16.04 and I have been trying to use it. But nothing is working. I have looked up various answers on askubuntu and I have been unable to fix any of the symptoms. The terminal refuses to open, but I have been able to use xterm from which I have been able to open the file explorer using nautilus command. However, I cannot open it via clicking on the icon. For the audio, I have tried using the guide mentioned here by installing Pavucontrol but that hasn't worked either. For the terminal, I tried following this but my system languages seem okay. Plus I have been trying to watch videos and even posting this question proved to be horribly slow, and this was not an issue ever before. I would really appreciate it if someone could help out here.
Edit : I tried changing the language to UK and making everything UK in the Languages section but that has not helped either.