wow strange behaviour.
The very basic solution to most of the problems is to restart the device by pulling the battery directly from the device while it is ON.
If you have tried this then check what is the level of sound in the field right below the ringtone selection menu.
I have Blackberry 9000 Bold. I have the following options in the menu right below
Your Storm device might be having numbers in ascending order in this menu.
Check the sound by selecting a higher number.
Hope this might resolve the issue.
Blackberry Support Engineer