I lost my clicker on my keys where I can turn off the alarm and when I entered my truck the alarm started off. It wont stop and I cant start the car with my keys.

You are most likely correct, it probably has an alarm. Unfortunately, most alarm systems are connected to the remote that is broken. You should have to have your dealership get you a new remote for the vehicle.

what make and model?

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.

you may have to insert the key into the driver door, and turn it to unlock, to disarm the factory system.

the car thinks it's been stolen

Replace clicker batteries leave them out and hit reset internal dot inside clicker !

change the battery's in the key fob

to disarm the alarm. turn the key in the door or trunk.

Sounds like a problem with the computer, or alarm system,
A budy of mine had a similar problem with the locks, it turned out that the alarm clicker was shorting out..

This worked on my car when the clicker died:

Put the car in valet mode. Disconnect the NEGATIVE battery terminal. Put the keys in the ignition and turn it as far forward as you can (as though trying to start it) and let it spring back. Reconnect the negative terminal. This should reset the alarm to valet mode. Programming varies from brand to brand. Contact an alarm dealer and they can help reprogram the remote(s).