The best is way to remove the bottom case/cover of your IPod and ID your flash memory part number. Do a search on the internet for its true physical memory size.
Otherwise you could read the following and do it without open your IPod:
Tool: H2testw - To test hacked flash memory
This might wipe out your existing media file during the process. Make sure you have back up of your songs, photo etc....
My suggestion:
Read all avialable postings from other smart users that related to your IPod Model before do anything.
You can accomplish this by searching your topic within this wedsite. See the search icon at the top of your screen.
This is how I learn from the best and solve my problems!
It took a while to learn and work on this unhack project.......
Be patient.
Hope this help