I think I have messed up big time all my websites.
6 months ago I decided to change the robots.txt files in 9 of my websites, a few weeks later I noticed a big drop in traffic(I thought it was the google updates), now 6 months later, none of them are indexed in Google, only bing.

I am now suspecting that my robots.txt files were wrong.

Could you please tell me is this code rejects Google bots please?

User-agent: *

I have now replaced everything with:
User-agent: *
Disallow: /cgi-bin/

Thanks for your help everyone,