I have bought this model but no manual but ii have the serial number how to find the combination?

You may find a manual, but it will not have the combination you are looking for but may have ideas on how to get it open.
http://www.manualsonline.com/
https://www.manualslib.com/

Visit the on-line store, know as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.
Best Manuals

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.

By Office1000 at 06/04/2006 20:46
"I bought a used Sentry Safe at a garage sale"

"I bought a business and it came with a Sentry Safe that is locked"

Help!

We get these requests everyday. Unfortunately, eventhough Office1000.com sells many Sentry Safe products, we don't have combinations for any of them. There is a quick and easy answer. It can be found on Sentry's webpage and we have reprinted here it for your convenience (though of course the details may be changed at anytime):

Lost combination:
First, find your safe’s Model and Serial Number.
The Serial Number is in this packet, and is also printedon the small label beside the door hinge (outside). Send a copyof this, a notarized letter (last name must be different than that of owner) stating you are the safe’s owner, and a check or money order for $12.00* (U.S. funds) to: Sentry Group, Dept. 200,
882 Linden Avenue,
Rochester, NY 14625-2784 USA.
If using a credit card (Visa/Mastercard only), call 1-800-828-1438
and fax your Model and Serial number with the notarized letter
to 585-381-2940.
That's it. It's simple.

We can't offer any further assistance on lost combinations or products not purchased from Office1000.com

If you made a purchase from Office1000.com (a Sentry Safe or anything else) and you need help, please use our customer service form and include your order number

IT SHOULD BE UNDER THE CARPET MAT.

I just bought this TV today. The number on the limited warranty is 1-888-977-6722. You will need to provide your model number, serial number and date of purchase.

Address to send registratin to is"

On Corp US, Inc
Product Registration Department
Parkwood Crossing,
450 East 96th strrt, Suite 500
Indianapolis, IN 46240

Hope this helps.

Lost your sentry safe combination. First, find your safe’s 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. just note your model # and the serial#. sentry safe lost combination and the opening instructions.

To bad you dismantled. Here is the turning sequence:
General Turning Sequence Instruction NOTE SAFE MODEL 5054/5055/5059/5080/5081/5084/5111/5190/5195/5575/5700/5702.

Combinations consist of FOUR (4) positions (numbers).
BEFORE YOU START
Before you begin, please clear all settings by turning the dial CLOCKWISE (to the right)
three times. We also recommend to try the procedure with your safe door open first. Then
follow these steps:
TURNING SEQUENCE
1. Start the dial on 0 (zero).
2. Turn the dial to the RIGHT, passing your first combination number FOUR (4)
times and stopping at that number on the fifth time around.
3. Turn the dial to the LEFT, passing your second combination number TWO (2)
times and stopping at that number the third time around.
4. Turn the dial to the RIGHT, passing your third combination number ONE (1) time
and stopping at that number the second time around.
5. Turn the dial to the LEFT, to the last combination number and STOP.
6. Insert the key in the cylinder lock and turn RIGHT to open.
Your safe should now be opened.

Do I need a remote or can it be unlocked manually? Yes press 0000