Unless the access point can contact a controller to get the instruction to ALLOW you to remotely manage it, you cannot.
how do your access points discovery your controller? DNS, DHCP?
What version did you upgrade from> to?
Type "show log system 50" on the commandline of your controller to see if you can see any ap activity.
Type "show ap database" to see if you can see any flags next to your access points.
Last but not least, type "show datapath session table <ip address of one access point you can ping>" to see if it is sending any traffic to the controller.