Software to increase my volume on iPod nano 6th gen?

I don't know of any software that can change the volume but you could use Apple Earphones with Remote to change the volume even though the buttons don't work.

http://store.apple.com/us/product/MB770G/B

I also found this, a remote that can be used with any headphones:

iLuv Universal Headphone Remote For iPod

I have the same problem also. I don't want to pay to repair it, as it will cost as much as a new iPod, since my warranty has run out.
I found a way to put your volume back to default (Middle. Halfway). Go to settings and select "Reset Settings". This won't delete anything on your iPod. However, if you are like me and increased the volume 100% in iTunes, make sure you take off your before playing music. :-) You can just change the volume settings in iTunes back to the normal volume. I did this, and now I can set the volume back to the middle wuth just a simple reset settings. Yay!