Speedometer won't work at all.

Could be speed sensor.

the tool Tacho Pro 2008 July can help you to solve it

It won't be a cable, as it's impossible for a cable driven speedo to perform this way.
It's an electronic speedo.

Check and/or replace the speedo sensor in the gearbox housing.

check the cluster fuse in the fuse box to the left of the dash

Try this. Turn the key on, do not start the vehicle. Absence the needle on the speedo. It should move down and then back up. Before it moves back up turn off the key. Repeat this until the needle is at zero. Then start the vehicle. If the needle goes back to a spot other than zero, you may have to take it for a quick drive, than the speedo head is likely bad. This is a pretty common an known issue for gm's. Let me know if you have any questions and I'll do my best to answer them. Thank you for using FixYa.com!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Is there an ABS light on also? I would suggest that you check for trouble codes first, but it could indicate that the vehicle speed sensor is faulty. Check for the obvious first, fuses, connections to the instrument panel, and trouble codes. Auto Zone and other stores offer computer code reading for free if you don't have the tool.

Year, brand, model would be helpful. You sure a speedometer cable is broke? If you have a newer car most of them have speed sensor(s). If a speed sensor is not working, it could be the problem with the shifting. Please rate my answer so I get points awarded.

The hand is usually pushed onto the speedo on splines so dismantle until you can get the hand then pull it off and put it to 0 and push it back on.

check for loose connection for the speed sensor or speed sensor itself is failing

look at the wiring from your stereo and make sure there are no wires earthing out that shouldn't be also check the fuse box for blown fuses