iPod Classic doesn't work after sync

My iPod Classic 160GB is having similar issues: can't sync or freezes with iTunes. Even though both iPod and iTunes are up to date and I'm doing everything on a Mac Computer.
I tried restoring it to factory settings 4 times. Erase everything from it. I am able to erase it all after waiting for hours of freezing iTunes and all.
But when I try putting back songs and content, it shows me I have "zero songs, zero videos, etc", even though my iPod shows I have "90GB of content".

I've been in this snowball forever!

My iPod was working perfectly fine until I decided to sync it back with my computer to upload silly 5 new songs I bought. Ever since then, I am unable to use it.
I tried everything, including formatting it through Disk Utility numerous times. Will someone please help me?