You can get a replacement for the stock connector. It's a special order from Metra, 71-1761. Assuming that your car did not come with System 10.
But that may not solve your problem. The Metra replacement has different wiring colors that the Toyota harness. You will need the original connector to find out which wire is which.
Of course, if you know which wire is which, then you don't need any Metra harnesses at all. Then you can just hardwire the aftermarket harness into your car's wiring loom. This is not the recommended procedure, but it is possible.
However, the best you can do is to try to restore your car to original with a Metra 71-1761 harness or maybe the Toyota dealer can help you. Did you even ask them yet?
If you go to a professional installer to have them sort it out, make sure they have the patience to determine correct polarity on the speakers.