I went to open my 2005 Toyota Corolla trunk using my car key. When I rotated the key, the mechanism went 90 degrees CCW but the trunk remained locked. I tried the trunk release in the car but it wouldn't release the trunk either. Went to dealer and they couldn't locate a rear seat release. I have an appointment in 2 weeks. Does anyone know how to get the rear seats down so I can access the trunk release.

Wrong keys or wrong car?. lOL
the cable release won't work if the trunk kew was in lock horizontal position. It needs to be vertical when key is removed. More penetrating fluid and try to force key rocking back and forth in and out. Use lots of wd40 or penetrating fluids and repeat. This will work. Also make sure you are using a master key only. Black top.

Torque:
- Connecting rod (big ends). Tighten bolts in several steps. 1st stage 29 NM, 2nd stage, rotate further 90 degrees
- Main cap bolts (crank shaft). Tighten bolts in several steps. 1st stage 44 NM. 2nd stage, further tighten 90 degrees.

Remove the rear seat back and cushion and crawl through and manually unlatch the trunk

Duplicate queastion.

Sounds like it. I would have it checked by a mechanic.

So then anybody can get in your trunk. You cant use the valet key to open the trunk, if you could, what good is it?

In my '04 corolla I can unlatch the left passenger seat back by reaching behind the left seat back and sticking my finger up into the second of 3 quarter sized holes. my arm is about 15" stuck in and reaching up into the trunk about 6" back. Feel around for the holes. You can pull the latch at that point, but...you have to be flexible.

the trunk lock mechanism might be jammed... if you have an access to the rear from the inside try pulling and moving some parts in the lock mechanism

On the V-6 it's 25 Nm (18 ft lbs) on the first pull and then you rotate the next pull 90 degrees using a torque angle wrench.

Checking the specifications for the four cylinder:
25 Nm (18 ft lbs) on first pull and 90 degrees
on the second pull using a torque angle wrench.

I have a corolla 2003 and I had the same problem. I turned the key to the left and the lock turned left, engaging the valet parking mechanism. I could not turn the key to the right and could not get access to the trunk because the lever next to the driver seat was disengaged.
The way I solved this problem is as follow:on the back driver seat I pulled the back seat forward to leave an opening and snick my arm in the trunck. Then I grabbed the cable used to latch the seat and I pulled forward, i.e. toward the front of the car. The cable is connectred to the trunck so that it can be disconnected easily if pulled towards the front. If you pull towards the back it will remain attached to the trunck. So grab the cable an pull towards the front, and it will release itself. Since the cable is flexible, you can pull it out of the trunk from the same the opening you put your arm, and then disenagage the driver back seat. Fold forward the back seat and get into the trunk and use the lever in the latch of the trunck to open it. The turnk will open.

If the lock does not turn, you need to disconnect the lock from the mechanism, so that the driver seat lever can start working again. To do this, and with the trunk open, remove the cover holded by nine plastic pins. Do not break the pins. After removing the cover, you will see the lock holded by two nuts. Remove the nuts with a rachet. The lock will be loose, and disconnect the lever that connects the lock to the latch. At this point the driver seat lever will start working again. Close the trunk and verify that the driver seat lever opens the trunk. Now you can open and close the trunk , and have time to call the dealer for a new lock.
Good luck.