Lost my contacts and they won't sync

I decided to reset my iPod back to factory settings because most of my apps had started to act weird saying they weren't connected to the internet even though safari had worked, but after I had reset my iPod I lost all my contacts, and I didn't back it up on itunes because all of my contacts are saved on my gmail account. But now when I've set up my iPod it says it'll only upload any new contacts added from my iPod. Does anybody know a way that I can get all the phone numbers off of my gmail account and back on my iPod?