Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
A question I must ask before I can offer any answer is, Are you the original owner of the Sentry Fire Safe in question, please?
Good. The original owner of the safe, in possession of the original bill of sale, can apply to Sentry to have the factory-set code (or 'original code', or similar) sent to you - if you are content with a time-frame on the order of a week perhaps ?
If so, let me know, and I will give you instructions.
The local locksmith will be expensive, and will possibly damage the safe to get it open.
But thank you for asking your question here at JustAnswer.com. And whatever course you choose, good luck with it.