I did some changes on my wi-fi connection to give ip manual and somethings else I do not remember what exactly i did and now Wi-Fi connection is not enable on the menu bar I set my connection again to DHCP but also I do not have any wireless access point. In that bar beside the time on the above there is **Enable Wi-Fi **which is inactive
Update:I did jgrocha's steps. after that I saw
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phy0: wireless LAN
Soft blocked: no
Hard blocked: yes
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I follow link and my problem solved