There are many operator makes and models, if your remote or keyless has a LED light on the device or your numbers on your keypad light up, then more than likely it isn't the battery.
You may have lost the code due to a power outage or accidently hitting the wrong numbers on the keypad or during the change of the battery.
What you will need is a ladder to reach your operator head, as there is a learn button or smart button depending upon what your model calls it. It is the programming button for your remote and keyless. You will need your remote that lost the code with you on the ladder. Position the ladder far enough away from the operator while still being able to push the smart/learn button. If programming a keyless you may need two people.
If you are programming a keyless entry, you will need the manufacture name and model and search the internet for instructions.
If you don't understand the instructions or you need help with programming the remote or keyless, give us a call at 513-872-0888 and we will be happy to help you!
Each manufacture has different instructions, but the above generally works. If the above instructions do not work then you will have to go to the internet and search for your make and model of operator (not door) and you will find the programming instructions.
Generally it is pushing the smart/learn button in and it starts to flash or remain solid, then hold down the remote button for a couple of seconds, the LED light on the operator should start to blink, push the smart /learn button again. Stand away from the operator and push the remote button in, the garage door should begin to move. MAKE SURE YOU ARE FAR ENOUGH AWAY FROM THE OPERATOR AS NOT TO HARM YOURSELF.