Checked my keyboard via DELL DIAGNOSTICS provided in resource DVD (included with my STUDIO 1555). All the tests were passed (Problem Existed)
After these things he told me that DELL tec. is gonna come and replace your keyboard with new one.
After this i made some tests myself, they are:
Checked via. external Keyboard. (Problem Existed)
Checked using Windows ® 7 on-screen Keyboard. (Problem Existed).
When i saw same thing is going on i came to conclusion that something is wrong with windows or a driver or may be some settings in control panel.
Now, today some hours ago i made my keyboard working smooth as butter.
>>>Region and Language
Window will appear
Click>>>Keyboards and languages tab
Click>>>Change Keyboards button
Another window will appear
Select default input language
In Installed Services there will be some added keyboards
i removed all keyboards there
and added new one as ENGLISH (United States) (United States Keyboard Layout).
Rebooted my Sys.
WOW! Keys are alive now, and are awesome.
i corrected this problem my self otherwise dell was going to Disect my new laptop and install a new keyboard.
I wrote this post to help others if they have the same problem.
Operating System: Windows 7 Ultimate (x64)
and yeah initially my keyboard layout was set to English (India) US Style..Finally it was English(India US Style keyboard) ERROR...Thanks to me as i got my keyboard fixed my self.And yeah! thanks to DELL online support team, thanks to dell as a whole org.