First question..did you change the dns information both with the domain register and with you host/name server?
If so, then some ISP's will pick up the change within 24 hours. Others could take 2 to 3 days.
If you want to check and see if the new site is simply not resolving from your location, go to
www.tracert.com. Pick a few locations and do a tracert on your domain name. You will be able to see if any of the locations are resolving to the new server. If after 48 hours, none of them are resolving to the new server..then you probably missed a step somewhere.