security / keyless entry problem

Last month, my keyless entry system stopped working. I tried deactivating the alarm with two different remotes I had, but neither one worked (they had both worked before the incident). I got into the car using the key but could not deactivate the alarm system when I put the key in the ignition.

I had to get into the dash and unplug the old radio with built-in security to deactivate the alarm and start my car.

I recently bought a used radio replacement on the internet, but it came without the grey security unit that screws into the radio. I tried installing it into my car, but the keyless remotes still did nothing even when I reset them to the new radio. What is the problem????? Does the keyless entry work through the radio or through the grey security unit that attaches to the radio????

Both. You still need the gray box. Its the brain of the alarm.