I ran a two way ANOVA to find effect of interaction between drug and food on size of plant. I found no significant interaction but both drug and food were significant, Now, should I switch to type II ss and just report F? or perform t-tests (as each factor has two levels)? please guide me on this
First, I don't think you need to "do anything" about not having found an interaction. You will report that as not significant. It means that the drug factor had the same effect no matter what the food factor.
I don't know why you would change the calculation of SS. For example, sometimes people fold non-significant interactions into the error term. But you've already shown that both main effects are significant so there is no point.
Your next step would normally be to conduct post hoc tests but with two groups in each factor, you don't need post hoc tests to tell you which means are different. If drug1 ad drug2 are the means for the drug factor, they differ. Similarly for the food factor.