Toyota avolon wont stop running when you turn the key off

It might have a passive anti-theft system and perhaps even a crude alarm system. I suggest you check in the vehicle handbook to be certain or ask your local Toyota dealer.

It's best you buy manual for this job. To many things need to be back in place. There are a lot of parts to remove .

It sounds like it thinks the key is still in it all the time. Try turning the key forward to the on position, but not running, so the dinging stops. disconnect the battery. Remove the key completely and reconnect the battery.

google 2007 Avolon electrical diagram or wiring diagram

Bad shifter or cable, or attaching hardware.

The alarm system somehow got activated , this is usually because the battery becomes discharged or disconnected try doing this:
Remove the key from the ignition
disconnect the negative battery terminal
put the key back in and turn to ON
exit the truck and leave door open
reconnect the battery terminal
get in and leave door open, if the alarm horn stays off it should start.

Sounds like you have a short in the electrical system.
Could be a bad ignition switch. You need someone to check for continuity. etc.

its on the left side of the engine below the exhaust manifold, best got at from underneath the car

i take it the key is turned back to off position then removed...if car still running they have common problem with the electrical part of the ignition switch

Sounds like you have a bad ignition switch. Not the key, but the electrical switch.