I had to reinstall ESO, but I saved my add on folder contents....
Does anyone know If I can drop the files from old folder to new??? or should I reinstall new add-ons... if I do I will lose some of my data stored like harvesting nodes I visited..
AddOn saved data is not stored in the AddOns folder it's stored in the SavedVariables folder. So you can re-install the AddOns all you want, the data they use is in a different folder.
You need to copy over your old C:\Users\<windows user name>\Documents\Elder Scrolls Online\live\SavedVariables\ if you want to keep your AddOn settings.