in ipad2 wifi signal is high. But when i enter the security password its say failed to connect the specific wifi rouhter

Look at iOS Troubleshooting Wi-Fi networks and connections http://support.apple.com/kb/TS1398

iPad: Issues connecting to Wi-Fi networks http://support.apple.com/kb/ts3304

iOS: Recommended settings for Wi-Fi routers and access points http://support.apple.com/kb/HT4199

Additional things to try.

Try this first. Turn Off your iPad. Then turn Off (disconnect power cord) the wireless router & then back On. Now boot your iPad. Hopefully it will see the WiFi.

Go to Settings>Wi-Fi and turn Off. Then while at Settings>Wi-Fi, turn back On and chose a Network.

Change the channel on your wireless router. Instructions at http://macintoshhowto.com/advanced/how-to-get-a-good-range-on-your-wireless-netw ork.html

Another thing to try - Go into your router security settings and change from WEP to WPA with AES.

How to Quickly Fix iPad 3 Wi-Fi Reception Problems

http://osxdaily.com/2012/03/21/fix-new-ipad-3-wi-fi-reception-problems/

If none of the above suggestions work, look at this link.

iPad Wi-Fi Problems: Comprehensive List of Fixes

http://appletoolbox.com/2010/04/ipad-wi-fi-problems-comprehensive-list-of-fixes/

Fix iPad Wifi Connection and Signal Issues http://www.youtube.com/watch?v=uwWtIG5jUxE

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If any of the above solutions work, please post back what solved your problem. It will help others with the same problem.

 Cheers, Tom 😉

If you have control of the router, some have reported connecting to wifi easier if they change security. Like go from WPA only to WPA/WPA2 or something like that (sorry, can't recall the exact letters)

So if it's your router try fiddling with that.