It sounds like you lost the first gear shift solenoid, here is a diagram (below) and a guide to help you get the problem fixed.
This is the bottom pan style you will need to pull the side pan so you may need to drop the sub frame a bit to get to it.
https://www.2carpros.com/articles/how-to-service-an-automatic-transmission
Please let us know what happens.
Cheers, Ken
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Wednesday, August 23rd, 2017 AT 4:47 PM