Q: My ipod shuffle 2 gen don't want to make volume down.

Have you tried a simple reset of the Shuffle?

Resetting iPod shuffle

Is your Shuffle model the one with the controls with into the headset or on the actual device?

Identifying iPod models

B-rock

Your next and only remaining option is to connect the Shuffle to your computer and perform a restore of it via iTunes.  This process wipes all content from the iPod, resets all settings back to their defaults, and reloads a fresh copy of the iPod's software onto the device.  See here for instructions on restoring the Shuffle.

Restoring iPod shuffle to factory settings

If a restore doesn't help, it rules out the probability of it being software related, meaning it's a hardware problem.  Your only option at this point is to either take or send your iPod in for service or replacement.

B-rock

In that case as I said above, it's hardware related, meaning you'll need to have the iPod serviced/replaced/repaired.

B-rock