Initialize disk warning after setup Security in Property

When I tried to access my second internal hardrive, I got a ACCESS DENIED error. So I went to Disk Management. I right clicked on Disk1, then property. I went to Security and saw that Full Control was not checked. So I checked on it. Disk Management ran and rebooted my win 7 Pro desktop. When it loaded it, my hardrive was not listed any longer. I went to Disk Management again and I got the Initialize Disk message (see below). I afraid to click on OK because all my data may be wipe out. Any helps will be greatly appreciated. I have a lot of data on my hardrive.