Good evening and welcome to Just Answer,
Your question is very common on our site and happens to many as lost combinations for their Sentry safe is asked on our site on a regular basis.
As for retrieving your lost combination, the recommended way to retrieve this would be to contact Sentry directly as they will be the only ones that will have your unique combination. Each safe has a unique combination as this is for security reasons as you will not want anybody to know how to open your safe. Sentry then will be the only ones who can retrieve this for you.
I have included the link to reach Sentry as follow the simple directions and your combination will be sent to you as soon as possible:
If your safe is not produced by Sentry, then please inform me and I can then research contact information for that company.
I hope that this information was found useful as please let me know of any additional questions/concerns you might have. Also if you could take a quick second to rate my assistance so that I know my help was found useful tonight.