If it's a HDD you might still have a chance to recover the key. Stop using the drive that had the old Win10 install immediately. Every usage has a chance to overwrite more of the deleted data making it unrecoverable. Boot from a different drive and scan the old drive with Testdisk, Photorec or some other undelete utility.
If it's an SSD with TRIM everything has already been zeroed out and you're hosed, sorry.
EDIT: Also, brute force is extremely unlikely to work. In this case you're not up against a password created by a human (a weak password can be cracked in minutes), but instead an extremely long randomly generated number (take longer than the age of the universe).
Last edited by ltpdttcdft; 03-09-2019 at 10:46 PM.