How to recover my bitlocker data in windows 7 to Windows 10, my pendrive showing blank

[pratik14]

When I am using windows 7 that time I have locked my pendrive by using bitlocker, now I have installed Windows 10 pro 64bit, so I am unable to open my pendrive and it's showing blank, there is nothing in that, but one thing I have old recovery key, please help me on this issue, it's very important documents in my pendrive

[WAWood]

@pratik14 

Given the date of your post, I would have expected someone to respond to it before this -- but since there is nothing WE can do about an encryption key that YOU apparently did not save offline, then there are no suggestions anyone can provide.

I use BitLocker on a new HP laptop, and the FIRST thing I did was export the key to a USB stick so I could recovery stuff later.  If you did not do that, then you should NOT have used BitLocker.