Do you have a more typical USB power adapter, like the one that comes with an iPhone/iPad (or other device). The first thing to do is confirm at least one of your USB docking cables works for charging at least one of your shuffles. Then, use that one on your computer's port and attempt to get a data connection (where the shuffle's light comes on and blinks amber). If the shuffle does not even charge from a power-only connection, you can't really move forward.
Alternately, if you have an Apple Store nearby, make an reservation with the store's Genius Bar (tech support staff). Take both of your shuffles and both of your USB docking cables. Figure out what is working and not working. If your computer running iTunes is a laptop, you may want to take it along too. You can make a reservation using the store's web page
https://www.apple.com/retail/