Unvalid output voltage of LM35 temperature sensor
The LM35 datasheet says absolute maximum rating for supply voltage is -0.2V.

It means that connecting it the wrong way to a power supply can damage it, and it does not have to work any more as the absolute maximum ratings have been exceeded.

Also the minimum recommended supply voltage is 4V, so check that your supply voltage is also 4.0V or more. It may not work properly at 3.3V.