If the computer is the original one used to encrypt the drive, the TPM chip holds the key. Booting into the BIOS/UEFI and resetting the TPM might force BitLocker to ask for the Recovery Key (if you have the 48-digit key). If you don't have the key, do not reset the TPM.
john --format=bitlocker hash.txt --wordlist=rockyou.txt bitlocker2johnexe extra quality