My external HD can't be detected..

Hello,

i really need your help.. my external HD can't be detected when i plugged it into my laptop.. there are many precious photo of mine and many precious data.. my life is in that external HD.. but i can'tt open the 'local disk G' .. i can open the other one.. but this local disk G ... i cant opened it.. when i tried to open it,, it said 'u need to format it before u can use'
.. what should i do to get or to recover my files?? help, please?? anyone .. :'(
(sorry for my bad language and grammar)
i don't understand everything about something like this ..T_T
o yeah,, i took out my hd from my laptop (toshiba)