How to disable Bitlocker through command prompt?

Solution 1:

at first sight http://technet.microsoft.com/en-us/library/ee706522(WS.10).aspx looks good:

• Manage-bde:
  This tool can be used to turn on or turn off BitLocker, specify unlock mechanisms, update recovery methods, and unlock BitLocker-protected data drives."

The site of Manage-bde gives:

-off 
Syntax manage-bde –off Volume [-ComputerName Name]

So, you can try to:

manage-bde -off F:

Solution 2:

This sounds like a hardware problem. My suggestion would be to first try to unlock the drive using the manage-bde utility.

1. Open an elevated cmd prompt
2. Type manage-bde F: -status and look under "Key Protectors" to ensure that "Password" appears.
3. Type manage-bde F: -unlock -pw and type your password to unlock the drive.

If this fails, I suggest trying to unlock the drive on another machine in case the hardware problem is on your first computer. The computer will need to have Win7 installed. Alternatively, you can create a bootable WinRE (not WinPE) DVD, which will also allow you to manage BitLocker and attempt to unlock the drive. Instructions for this are here here.

You said that the recovery key is lost but if you have the recovery password (the 48-digit number generated during BitLocker setup) you can recover the drive using the repair-bde command line tool included in Win7. If your computer was connected to a network with Active Directory, your recovery password was backed up to AD and can be recovered by contacting your AD admin.