How to unlock BitLocker under Win7

Now Windows7 is too powerful, sometimes it’s awkward, it’s awkward, do you say it? Let’s take BitLocker and say ——
Windows7, in order to protect the data, the E drive BitLocker encryption. However, after reinstalling the system, the E disk cannot be accessed. Double-click the E drive and no password input window pops up. Right click and select “unlock the drive” nothing happens. What should I do?
In addition to reinstalling the system, when removing a hard disk containing BitLocker drive encryption or moving the hard disk to another computer, the password input window may not be popped up and the data cannot be accessed.
Workaround:
Written in front of the text: After using Bitlocker encryption, you must have one of the passwords or keys to open or restore the relevant files from the perspective of the user's information security. If you forget your password, you must find the backup key to open the file. If the key is not found, the encrypted file will basically not be opened...
If you have a key, you can use the administrator command to unlock the drive. The details are as follows:
In the Start menu, open “All Programs>Accessories> Command Prompt”. Right-click on the "Command Prompt" and select "Run as administrator" ”.
If a User Account Control (UAC) window pops up, please allow to continue.
Type the following command on the command line:
manage-bde –unlock E: -RecoveryPassword ******
Note: “******” Part of BitLocker Recovery The key is not the password we set ourselves (as shown in the yellow area below); in addition, please pay attention to the space.
Unlocked successfully:
Reminder: After BitLocker encryption is removed, in order to avoid the situation that the password window cannot be popped up again in the future, it is best to unlock the drive first and then reset BitLocker encryption again.
Do you think the Windows 7 system is very useful?