The issue is as I said in the
last paragraph of this post - though not as explicitly as I should have. The data in the Google geolocation database for your IP address wrongly places you in Greece, so all Google powered services (YouTube, Adsense etc.) believe you are in Greece. The RIPE Whois data being correct is a good sign, as it indicates the address block is correctly registered for its current use.
Google tend not to accept geolocation database corrections from members of the public, hence my suggestion to contact your ISP and ask them to send a correction to Google.