I do not know serial number and lost keys to safe

Call 1-800-828-1438 with the serial number of the safe.

Details how to obtain a replacement key and where lock number etc are located at the link below.

http://www.sentrysafe.com/CustomerCare/Need_A_Key

To order replacement keys, for small chests and files, you will need to know the key numbers which can be found right around where the key goes in. It should be a stamped number, letters, or both located around the keyhole. For Personal, Home and Home/Office Safes, you will need the model number and serial number. I think that the most economical place to buy keys is from www.SentrySafeShop.com. You can do a search for "lost keys" and it will give you a screen where you can enter your model number and key number. (It is a very easy screen to use. They just need 1.)Model # and 2.)Serial or Key #.)

In Summary:
For Small Chests or Files: A lock reference number is required. It will be a letter, a number, a letter and number, or "blank" (no letter or number), engraved/located on the silver cylinder of the lock. These are model numbers 0500, 1100, 1170, etc...

For Personal, Home and Home/Office Safes: (model numbers will begin with: S0, S3, S4, S5; I0, I3, I4, I5; A3, A4, A5; J3, J4, J5; L0, L3, ,CS,CSW,DA,DS,KS,KSW,MS,MSW,OA,OS,and SC): Indicate your model number and the safe serial number found on the front right-hand side of the door, between the hinges.
Here is the direct link to the key replacement screen: http://www.sentrysafeshop.com/Keys-Sentry-Safe-Replacement-Keys-p/keys.htm

Locksmiths agree there might not be a serial# but there is a key # Sentry Safes Keys. Lost your Sentry safe keys. just note your key #(on lock) It's above the keyhole example 3J2, C003B, H,

Sentry Safe lost combination. First, find your Sentry Safe's Serial Number. The Serial Number is printed on the small label on the right side of safe, on paper tag near bottom hinge, below the cover plate or you can look behind the handle with a mirror. Just note your model # and the serial #.
Sentry Safes express combination research is fast with a next day Service. The email is sent the next business day with the sentry safe combination and opening instructions. Although there is a service charge it's still cheaper then locksmith drilling a Sentry Fireproof Safe open.

To order replacement keys, for small chests and files, you will need to know the key numbers which can be found right around where the key goes in. It should be a stamped number, letters, or both located around the keyhole. For Personal, Home and Home/Office Safes, you will need the model number and serial number. I think that the most economical place to buy keys is from www.SentrySafeShop.com. You can do a search for "lost keys" and it will give you a screen where you can enter your model number and key number. (It is a very easy screen to use. They just need 1.)Model # and 2.)Serial or Key #.)

In Summary:
For Small Chests or Files: A lock reference number is required. It will be a letter, a number, a letter and number, or "blank" (no letter or number), engraved/located on the silver cylinder of the lock. These are model numbers 0500, 1100, 1170, etc...

For Personal, Home and Home/Office Safes: (model numbers will begin with: S0, S3, S4, S5; I0, I3, I4, I5; A3, A4, A5; J3, J4, J5; L0, L3, ,CS,CSW,DA,DS,KS,KSW,MS,MSW,OA,OS,and SC): Indicate your model number and the safe serial number found on the front right-hand side of the door, between the hinges.
Here is the direct link to the key replacement screen: http://www.sentrysafeshop.com/Keys-Sentry-Safe-Replacement-Keys-p/keys.htm

You can go to www.SentrySafeShop.com and do a search for keys. You will then be able to enter your information as listed below and they will send out a new set to you. Much cheaper than having to destroy a perfectly good safe to get into it.

For Small Chests or Files: (Model numbers will begin with 1100, 1160, 2100, etc... ): A lock reference number is required. It will be a letter, a number, a letter and number, or "blank" (no letter or number), engraved/located on the silver cylinder of the lock (right around the hole where the key goes in at).

For Personal, Home and Home/Office Safes: (Model numbers will begin with: S0, S3, S4, S5; I0, I3, I4, I5; A3, A4, A5; J3, J4, J5; L0, L3, ,CS,CSW,DA,DS,KS,KSW,MS,MSW,OA,OS,and SC): Indicate your model number and the safe serial number found on the front right-hand side of the door, between the hinges.

You can go to www.SentrySafeShop.com and do a search for keys. You will then be able to enter your information as listed below and they will send out a new set to you.

For Small Chests or Files: (Model numbers will begin with 1100, 1160, 2100, etc... ): A lock reference number is required. It will be a letter, a number, a letter and number, or "blank" (no letter or number), engraved/located on the silver cylinder of the lock (right around the hole where the key goes in at).

For Personal, Home and Home/Office Safes: (Model numbers will begin with: S0, S3, S4, S5; I0, I3, I4, I5; A3, A4, A5; J3, J4, J5; L0, L3, ,CS,CSW,DA,DS,KS,KSW,MS,MSW,OA,OS,and SC): Indicate your model number and the safe serial number found on the front right-hand side of the door, between the hinges.

To retrieve your lost sentry fireproof safe combination. First, find your safe's Model and Serial Number. The Serial Number is printed on the small label on the right side of safe (on paper tag near hinge) or under handle. As this information is confidential a valid credit card and email is needed to verify a customers name and address
sentry safe combination archives searches. Do come with a service charge although it's definitely cheaper then buying a new home electronic sentry fireproof safe.
A good locksmith should be able to help you with the dialing programming instructions and lost Sentry Safe Key Replacements

To retrieve your lost sentry fireproof safe combination. First, find your safe's Model and Serial Number. The Serial Number is printed on the small label on the right side of safe (on paper tag near hinge) or under handle. As this information is confidential a valid credit card and email is needed to verify a customers name and address
sentry safe combination archives searches. Do come with a service charge although it's definitely cheaper then buying
a new home electronic sentry fireproof safe.
A good locksmith should be able to help you with the dialing programming instructions and lost Sentry Safe Key Replacements.