Use of Security in win 7

I have hidden a partition of my hard drive bty right clicking the drive and going to option of security.
The drive became inaccessible to other users, but now I am myself unable to access the partition.Although I have permissions and have allowed for all the permissions.
If some one knows the answer to this problem please do tell me thanks.as my important data is inaccessible
Thanks

Try disabling other user's accounts then try to access it again under admin account.

Logon as an Administrator.
Right click the folder or file you need to change.
Select Properties.
Click on the Security tab.
Click on the Advanced button.
Click on the Owner tab.
Click the Edit button.

Thanks for your reply
I tried but a small window pops with the message that

" An error occured while applying security information to:

G:\

Access is denied."

( G is the drive which has been hidden)

Are we talking about laptop/PC - win7?

Have you tried booting into Windows 7 in SAFE Mode 'F8' to try it?

Yes we are talking about Desktop PC - Win7
I also tried in win7 safe mode but the result is same