1995 ford explorer alarm will not work after sitting in driveway for a long time without battery?

My '95 Ford exporer sat in the garage for about a year and a half and the battery ran down.
After replacing the old battery with a new one, it started fine and it ran great but the one thing I
noticed is that the alarm no longer works when I tried to press button on the alarm fob. I also replaced the battery on the alarm remote in case its battery also died. Alas it still did not work. I also tried to unlock the driver door using the code that I had written down and used to use but it too did not work.
I heard that there's a way to make this work again but I can't seem to find it in the internet. I tired the restting the keyless entry procedure from the internet but it did not work. I'm tempted to take it to the dealer but since I'm a single parent and have a teen ager who will be driving soon, I would prefer the alternate method first. The dealership is too expensive for me.

It probably needs reprogramed.

Call the local Ford dealership and ask the Service Manager, or stop by. Good advice is usually still free.

You will also notice that the radio won't play, until you enter the reset code for it as well. If you don't have the code, you'll need the serial number which should start with an M or V followed by exactly 6 numbers. You can get the M codes here, the V series will come from Ford dealer or a radio decoder service. But that's another topic. Back to your question…

Reprogram ford Infrared transmitter keyfob/door entry code
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obtain all keys and remote controls (all have to be done [up to 4] at one time)

Close all doors
Switch ignition on/off 4 times within 6 seconds total time
Turn off ignition
Program mode should now be on for 10 seconds confirmed by an audible warning and the LED system light on the dash
- press and release the lock or unlock button on the keyfob
- Audible warning will sound and the LED on dash will flash to confirm it has been done
- repeat for next keyfob (up to 4 in all can be done) within 10 seconds of the above.

Exit program mode by switching ignition on, or starting the engine and wait 10 seconds.

If the above process fails you will need a Ford dealer to assist.

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Your personal door entry code will have been erased with the loss of the battery connection. You will need to use the factory code to set a new personal code.

The code is found on your RAP module - to locate it, you might want to visit this link… In the picture, the code is covered by black electrical tape, for that owner's protection.

http://www.explorerforum.com/forums/showthread.php?t=192268&highlight=rap+module

additional related thread on the same site:
http://www.explorerforum.com/forums/showthread.php?t=260977

These videos may also help locate the module: