How can I get back in to locked partition?

I have a Compaq laptop with Windows 7 Professional pre-installed. I recently dual boot installed Windows 8 on it. I partitioned my hard drive, using Partition Wizard Bootable, in to 3 parts: C: (Where Windows 7 is installed); D: (An empty drive) and E: (Where Windows 8 is now installed). I took some space from D: and created E: with it. I then installed Windows 8 on the new partition.

Everything worked fine on Windows 8 until I tried to boot back into Windows 7. It displayed an error screen saying:

Windows Boot Manager  

Windows failed to start. A recent hardware or software change might be the cause.  
To fix the problem:

  1. Insert your Windows installation disc and restart your computer. 
  2. Choose your language settings, and then click "Next."
  3. Click "repair your computer."

If you don't have this disc, contact your system administrator or computer
manufacturer for assistance. 

  Status: 0xc000000f

  Info: A required device isn't connected or can't be accessed.

When I went back in to Windows 8 and looked at the disk partitions it didn't show any info about the disk. (e.g: Space, Percentage of disk space, etc.) After looking deeper (I can't remember where) I came across an error saying that the hard disk was locked. Whenever I try to open the drive to access my files it asks me to format the disk. Doesn't that defeat the point? I really need the files, they're mostly for my work! It's my work computer, and we have paranoid admins who don't even let us backup. It's surprising I was even able to burn the disk.

1. try Spinright: http://www.grc.com/sr/spinrite.htm
2. mount the HDD on another computer and try using "recuva" http://www.piriform.com/recuva although I am not sure it will be able to read the drive.

Spinrite can really works but can take a couple of days if running on a deep level. You can "find it for free" if you don't have the money but you should of course support the developer if it works out well in the end.