I would recommend you download any two or more anti-virus software such as AVG Malware bytes and run them both( one at a time) until you get zero viruses, malware, Trojans, etc.
I don't think you can buy any amazon gift cards if you don't have a credit or debit card. The best option would be to go to your local electronic store and see if they sell them there. Do you have Wal-Mart's in Europe?