This shows: Upozorenje Resource string (plugins.pickup.pickupinstore.addnew) is not found. Language ID = 3 11/06/2019 16:05:52 Upozorenje Resource string (plugins.pickup.pickupinstore.fields.store) is not found. Language ID = 3 11/06/2019 16:05:52 Upozorenje Resource string (plugins.pickup.pickupinstore.fields.pickupfee) is not found. Language ID = 3 11/06/2019 16:05:52 Upozorenje Resource string (plugins.pickup.pickupinstore.fields.openinghours) is not found. Language ID = 3 11/06/2019 16:05:52 Upozorenje Resource string (plugins.pickup.pickupinstore.fields.name) is not found. Language ID = 3 11/06/2019 16:05:52 Upozorenje Resource string (admin.configuration.plugins.discardchanges.progress) is not found. Language ID = 3 11/06/2019 16:05:38 Upozorenje Resource string (admin.configuration.plugins.applychanges.progress) is not found. Language ID = 3 11/06/2019 16:05:38 Upozorenje Resource string (admin.configuration.plugins.discardchanges) is not found. Language ID = 3 11/06/2019 16:05:38 Upozorenje Resource string (admin.configuration.plugins.applychanges) is not found. Language ID = 3
...I would re-install plug in but can not find download files...
It would be better to reinstall rather than trying to "add those strings manually", in case something else is wrong too.
You don't need to "find download files" - it's already in your /Plugins folder. In the Admin > Local Plugins, Uninstall the plugin, Apply, and then the site will restart. Then go back to plugin list and Install and Apply.