How do you open a sentry safe if you don't have a key?

To open a Sentry safe without a key, you can try contacting Sentry's customer service for assistance, as they may provide a replacement key if you can verify ownership. Alternatively, if the safe has a combination lock, you can attempt to reset it using the factory reset method, typically found in the user manual. For more complex locks, it might be necessary to hire a professional locksmith. However, attempting to force open the safe can damage it and void any warranty.