Hi, martievatalaro,
Thanks for visiting the Apple Support Communities. Based on what you have described, it sounds like you might have a set a password on the Time Machine backup: About the Time Machine backup password on Mac - Apple Support. If this is the case, you must enter the correct password in order to restore that backup. You cannot reset or restore the password to get access to the backup.
That said, it is also possible you have a FileVault or firmware password set on your Mac. Check out the information in the below resources to get more details on what each password is used for:
Use FileVault to encrypt the startup disk on your Mac - Apple Support
Set a firmware password on your Mac - Apple Support
Each of those resources discusses what to do if you've forgotten the respective password, as well.
If you need further help with the password, you'll want to get in touch with Apple Support directly, as they'll have access to the necessary tools and resources to further assist.
For help with a firmware password, you'll actually need to take the computer into an Apple Store or Apple Authorized Service Provider. You can find locations, get contact information, and set reservations here: Apple - Find Locations
For more details on the Time Machine password, help with FileVault, or if you're still not sure , you can reach out to Apple Support directly here: Get Support.
Have a wonderful day!