I though the said "it cannot detect!!!" ... ?
Go into Control Panel > Admin Tools > Computer Managements > Disk managements

Check there if the disk listed there first. If yes, but unable to access, reformat (don't worry!!!), then use softwares to recover all your data. If you got the correct softwres you can recover up to 99.9% of data, except 0.1% might be on bad sectors... LOL...