I had a disease problem & lost all my plants /or I am starting over from scratch. How do I eliminate the risk of the bugs/disease still being in the area waiting to re-contaminate my new garden?

Scrub the area with food grade peroxide OR you can use bleach but you must try & clean the entire area to get rid of all bugs/diseases. A 10% bleach 90% water solution will remove disease/bugs/pathogens.