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i executd the cmd reset system on my WLC 4402 and after that i lost all the APs that were joined to the WLC,how do i get the APs back.
Try setting Master Controller Mode on your WLC (it can only be enabled on one controller at a time).
Also, you can bounce the APs (if they are on PoE switches by doing a SHUTDOWN and the then a NO SHUTDOWN on the ports feeding the access points.
In certain situations, this has gotten the APs to connect.
You may also want to check your IP address settings because if you had not saved your settings prior to the reset, they may be lost/reverted to default settings.