If your Bitlocker key is not working, are you sure that is the correct Bitlocker Key for your device, have you checked on your personal account and any work or school account that may be linked to the PC?
Are you currently unable to access Windows, and are you in the recovery environment?
If you are unable to access your device, do you have a safe backup of your files, or use a cloud service like OneDrive to sync your files online.