No robots.txt file

Hi.

My problem is that I don’t have an virtual robots.txt file.
There is no robots.txt file in the root directory of my domain either..

I have installed my blog (on my own server, MAMP, on my Mac).
Yesterday I added it to Google Webmaster Tools. I woke up today with multiple errors about the robots.txt-file not accessable. I tested, and I could not access the file either. I have tried to disable all of my plugins (including All In One SEO-pack, Google Analytics for WordPress, Google XML sitemaps and Maintenance Mode), but that did not work.

I’m pretty lost right now, haven’t got any idea of what to do..
I know WordPress generates a virtual robots.txt-file, but I should be able to access it throught my browser, shouldn’t I?

Thanks.