If no tax was withheld, then ignore the 1099-K. If you get a letter from the IRS, you can explain that you have no US-source income because, although you sell merchandise in the US, you have no physical presence in the US.
(Did you have a green card? If student visa, did you really get an SSN or was it an ITIN -- international tax ID number. ITINs expire if they are not used. I don't know if this will affect you. You might need to apply for a new ITIN if you get a letter that the old one is expired, but that does not make your income taxable in the US. If you have a green card, then you are subject to US tax on all your world-wide income until you surrender it. You have to file a US tax return for your world-wide income, but you get a credit for foreign taxes paid on the same income.)
