Unicorn hat hd no sound

After I installed the hat and ran it the pi has no sound even with the hat removed and restarting the pi ,I have tried the boot .txt force hotplug thing however the system refuses to save the txt and closes,what is the fix or how do I reactavate the sound

What was your sound source, HDMI, analog etc?
To edit the config.txt file its
sudo nano /boot/config.txt
Make your edit then press the Ctrl and x key, then y to save it. And reboot.

                                                     Thanks ,I will try your instructions and I hope it works ,but why Pimoroni  does not fix their apt that runs the unicorn Hat HD,I should not have to do this,I will think long and hard before placing another order.Think like this ...You purchase a new product for your home heating system and now you Television stops working and the way to fix is to edit the television to fix a problem in the heating system .HOW about a warning in the product description??

Are you sure it was the Unicorn Hat installer that did it?
It uses SPI which shouldn’t do anything to sound?
What were you using for sound, HDMI or Analog out?

What is your planned config.txt edit?

I was going to suggest to do a new Raspbian sdcard flash

I did an entirely new flash I did not install unicorn hat hd .Every thing works perfect no I will not install unicorn hat hd untill someone comes up with a fix .

I’ll ask this one more time
“What are you playing your sound through?”
HDMI or Analog Audio etc?