Disconnect the cable from the A/C adapter and connect the iPad to your PC via USB.
If windows or iTunes recognize the iPad has been connected then your cable is fine.
If the PC does not see the connection to the iPad you know your cable or the port on the iPad is likely the culprit so try a different cable and if the PC still fails to detect the iPad connection you know your cable is bad.
If with a second cable the PC detects the connection your problem is likely being caused by an issue with the iPad itself whether that be a bad port or a problem with iOS (I would lean towards the port).
There's also the possibility that it's not the cable but the a/c adapter that's bad.You should check by using a different adapter with a known good cable before concluding that the iPad is at fault.