I unknowingly purchased two used thongs from online seller. i thought they were new. i washed before wearing, (wore few times) but could i get herpes from this? (or any stds/stis/herpes from their worn thongs?) or from touching them with my hands?

It seems unlikely the thongs had been worn before selling, but even if that happened and even without laundering, there would be little or no risk from herpes, which is rarely if ever transmitted by shared clothing. With washing, the chance of such infection for sure is zero. This is nothing to be worried about.

No, herpes or STD transmission is not possible in above mentioned circumstances. Check cdc.gov for reliable information regarding herpes and/or STD’s in general.