Alarm wont stop going off. Car wont start. Any way to disable it?

Disconnect the battery, have the ignition key turned to the "on" position then reconnect the battery.

The steering lock may be binding the ignition lock cyl preventing the key from turning or the key may be worn out. Try turning the steering wheel back and forth while wiggling and turning the ignition key. To get the alarm to turn off without starting the car try locking and unlocking the vehicle from the passenger side door. There is a micro switch on the drivers side door lock cyl that may be bad and preventing the alarm from dis arming. This is all providing it is a toyota factory alarm sys.

Same here... I have a 1998 Toyota Avalon XL. My car battery died. Replaced my car battery, but found out that when you unplug and plug the car battery with this car it engages in security mode (I have factory car alarm). This disables the engine and wont let you turn the ignition aka start the car engine until the remote (keyless entry) "UNLOCK" is applied. My remote is also lost so I cannot disable the alarm.
The only thing I can think of to do is unplug the battery again to disable everything (car alarms are annoying...) and call the dealer to pick the car up and perform the diagnosis. Most likely they will offer you another keyless (ugh... expensive) and/or you could ask to disable the factory car alarm.
I know thats not much help but it seems to be the only option from what I researched currently....

With alarm activated your ignition is disabled.Find the combination to disable it.With GM's you hold opposing buttons on the fob till it beeps twice. The dealer should help for no charge.

Maybe your key remote batteries need to be changed. Also have it scanned for DTC's which I believe you may have quite a few stored in memory, problems you weren't aware of.

put your key in the ignition and start the car it will go off

the passenger side door lock will work to turn off alarm i'm having the same problem my car wont start cause the alarm is on and both of my door locks are broke so i'm trying to disable the alarm.

'99 camry: with alarm sounding. turn key to "ON" position and press in and hold alarm button (red two position (in /out) on dash board. Button should go from flashing red to solid red. Release button when it stays lit (solid bright red) . Alarm is now in disabled mode and engine should crank when key is turned to "start" position. "Thank you" for over the phone tech support at Richardson Toyota in Texas.

I had same problem, when a door lock broke, the car thinks it has been broken into once the alarm goes off. Mine started going off randomly when this lock broke. You have to reset the alarm system, with my 1990 Acura it was reset finally by putting key in door lock and turning key back and forth 3X. In my car, it was OK to do the key in door lock cycle in the passenger side door lock, but Acura dealer told me not all Acuras will reset it via passenger side key cycling, some require driver door lock key cycling only. I was lucky since my driver side door lock was currently useless, that my car allowed it to be done by key cycle on pass. door lock. But try that and if it doesn't fix it, just call acura dealerships until someone tells you the right answer. In my situation it took 3 dealerships with 3 different answers until this was the right one for my 1990 Legend.

PS I was told you can't disable alarm since it is all integrated into the battery and starting system, but read on another post that someone disableld theirs by disconnecting the horn.