I wrote to a public company twice and did not receive an answer, so I wanted to know if such companies have obligation to answer investor questions?
If you are a small investor it is unlikely they will bother to answer you. But for a big investor (20% of the stock) they would know you, you would have personally meet the top management and they would reply to you.
If you are a small investor in a big company, the best solution if you want to be heard or have questions answered is to team up with all the other small investor so all of you combined reprensent a significant % of the stock value.
I don't think there is an obligation to answer but it could be the case for some countries.