What should I do in different world?

On a certain morning a metabolic 35 year old salary man was suddenly transported to another world.

Without knowledge, without the ability to communicate, and I am especially not confident about my physical capabilities. I have no idea what to do.

However my current goal is to figure out how to keep living using the skills granted to me from the existence known as the interface.

Hero? Demon King? I know nothing about that. I am just a salary man.