problem with connection

Hi,

I have a big problem and I really tried everything. I cannot connect my iPod Classic to my Mac Book Pro 2015. Actually it can connect, but not to iTunes and I can`t restore it sadly. The problem became when I was synchronized my music, it was more than 4000 song but I let my Mac working, but it has slept already a the process was stopped.

First iPod showed that there is 160GB free (I have 160 GB version), but there were 30GB of music which I can listen to. But iTunes can read it. Then I restard my iPod and iTunes cannot read that at all and after that when iPod is ON it showed that here is only 130GB free but there is no data at all...

I already tried reformat a repair it, and it did not work.

Thanks a lot!!!!

(the think is that before this all problem I reformat iPod to OS)