My external hard drive cannot open

Hello,
Any one from you can give solution for open my external harddisk? my external harddisk cannot open. the comand is "device is nnot ready". And i see the properti think that tell the hard disk in blue cover ( Full file). The how can i open it and delete some data or move my data to another drive?? can be the data or file inside my external drive didn't lose or broken??
I ' am so damn panic, coz all the important data is inside the drive... So any one can tell me how can i fix this problems??
Plzz.. inform me.. Thanks