2000 Toyota Corolla ignition switch?

Sounds like the ignition switch or the wiring to it. I would take it to a good locksmith and have it checked. You can buy replacement switches, but then the ignition key would only work in the ignition.
If the locksmith has to replace the switch he can key it to work with the original key.
You can also call Toyota and ask for prices, but a locksmith is usually less expensive (in my experience).