When i try to run nxt server i get the message on the screenshot. I tried downloading it again and opening router ports, but im new, i dont know whats wrong, could i get some help?
It looks like you already have a node running.
Try just restarting the PC. If the problem persists delete the directory C:\Users\mateo\AppData\Roaming\NXT\nxt_db which contains the database and start the node again. This will trigger de re-download of the blockchain.