How do I fix an iPod that won't hold a charge and connect to my iPhone?

Have you tried another cable and have you ensured that there is no dust or debris in the iPod's dock connector? Also, is the power source working?

If all of the above has been confirmed as okay, perhaps the battery has failed and will no longer accept a charge.

If you do get the iPod working, note that you cannot connect it to an iPhone.

check the charger and dock or replace the battery