I have changed My Ip.I have tried different computers so I know there not installing spyware,is there any other way I am blocked?
How do you exactly know that you're blocked? Do they show you a message saying "Blocked" or something? I've never heard of Youtube blocking people, but they ban and freeze accounts. Is this the case?
You mean changed IP but with same ISP as Adam Rock posted? Try a different ISP or try a VPN like HMA and see if you're still blocked. Accessing through the same ISP, specially if you've just changed IP by rebooting your modem, won't do good sometimes.
I don't get how your "blocked" from your youtube, You can't go to youtube.com at all? You on a school network or something lol.