You need to find out whether your isp is blocking all packets, or simply using dns blocking. If its the former, then you will have to use a vpn or proxy to bypass it. The latter is easily bypassed by using an alternative dns provider like google dns, or blockaid.

I'd run a traceroute to megaupload and if it gets stopped before it reaches the site, that should confirm that they are blocking all packets. If you're on windows you can do this by opening up command prompt and typing 'tracert megaupload.com.'

Hope this helps.