How can I change my public IP address?

"since you don't elaborate on your reasons, we can only guess :)

if it was just for surfing, most free proxy services offer sufficient speed. downloading files, however, is quite a different affair.

so, if your concerns involve torrent downloads, consider a seedbox (a private dedicated server used for uploading and downloading files - quite popular in the torrent scene). such services ain't free but they offer privacy and speed.

download the torrent file (which is tiny) through a free web proxy, fire up your seedbox and let it do the dirty donkey work.

10 Really Cheap Seedboxes That Anyone Can Afford"

"I'm getting my IP through DHCP

The IP you get through DHCP is just your internal one, normally something like 192.168.x.x, not the external one.

To change your external IP without a proxy you would have to disconnect from and reconnect to your ISP.

Your operating system itself can't change this one."

"With DHCP, you're not going to be able to control the IP address you're going to receive. You may be able to unplug your router/cable/dsl modems and let it sit anywhere from 2-20 minutes, then plug it back in. At which point, you may get a new IP address from your ISP, tho it may be in the same range.

That said, I have Cox High Speed, and sometimes, I get a completely different IP's when i reset my modem. Your Mileage May Vary"