we cannot increase the volume and we have never put a password
need to know how to increase volume. it is asking for a password and it has never had a password
Model A1137 / 1, 2, or 4 GB capacity / black or white plastic front
Sounds like volume control is enabled. If you go into settings, you should see a toggle which mentions maximum volume. If you do not know the password, you'll need to restore the iPod.
To get the music off the iPod, use this program. Plug the iPod in and a dialog box should pop up. You'll want to hit the button that says something along the lines of "quick restore". After this, follow any instructions that the program gives you. When it is finished, your music should be transferred to iTunes.
Next, plug your iPod into iTunes; you should see the iPod appear in the main iTunes window. Inside this window, there should be a button that says "Restore". Click this, and iTunes will nuke all previous data on the iPod- including the passcode for volume control.