How do I stop my car from beeping,telling me the front doors are open when not?

What is your question?

The dash light is on showing front doors are open with an almost constant beeping, especially when turning left? I was told before that it was a bent sensor and when bent back in place it stopped. That was two years ago and now it's beeping again. How can I make it stop without a costly repair? Where are my sensors located? Thank you for your advice.