I downloaded the free Spotify while I was studying abroud in the Netherlands, but now I have moved back to the USA and I can't use the free Spotify anymore. Can I change my country without upgrading? Please help.
Yes, you can, although you will need to enter credit card information (a US credit card) in order to change your country. Entering your payment details will allow you to change the country on your account, and unless you actually upgrade your account, the card will not be charged. The credit card allows Spotify to validate the address so people don't abuse the free service by changing their country whenever they are travelling.
If you are unable to update your account in this fashion, you will need to contact Spotify directly in order to have your account updated. To do this, go to the Contact Form, which you can get to by following the "Contact" link in the "About Us" section on the footer of this page. Try to give them as much information as you can about the situation so they can locate, verify and action your account appropriately.