What can I do if someone has illegally occupied my goods?

I had imported gym machines from China in my name 5 years ago. There was talk of purchasing those machines through a friend of mine, and at that time he gave me some money in advance and it was said that the rest of the money would be paid after a few months. But till date he has not given me that money. I have the papers for import of machines, and my friend does not have any bill or paper of any kind, nor does he have any such bill. I now want my machines back, can I get my machines through asset capture or any other legal means.