It's very strange because, most westerners can get a tourist visa at the airport and renew it every month. If you are from a western country you don't need a sponsor to enter the country, so they must have found a pretty serious reason to deny you. Is it possible you are on a watch list? Many people here in the US have been placed on the watch list by mistake so that might be something you would want to look into. Regardless, they should have given you a reason for turning you away.