out of the blue the speedometer stopped working?

Surquty? what is that? scan for codes and check fuel pressure with a gauge auto parts rent it.

The radio and speedometer are not connected unless the alternator is throwing AC voltage. If you go down this guide it will show you how to test for that and if AC voltage is found the alternator needs to be replaced. If not I would replace the VSS sensor.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Here ikjs how to change the alternator out and the location of the VSS sensor in case you need it. Check out the images (below). Please let us know what happens.