Hello fouadissam,
You can connect to the AP with a console cable and enter show ip interface brief, which will display the ip address.
If its connected to a network you can log into your switch and enter show arp | i xxxx.xxxx.xxxx(mac address of the AP).
The below link points to a configuration guide that may be helpful.
http://www.cisco.com/c/dam/en/us/td/docs/wireless/access_point/15_2_4_JB/configuration/guide/scg15_2_4_JB3a.pdf
Hope this helps,
Please remember to rate helpful posts.
Thanks.