If you're trying to unblock Youtube through work or school then you need to use a VPN to get through to Youtube when it's blocked.
Sometimes you could also use an online proxy website to bypass any blocks on youtube as well.
However there's no guarantee that you can get completely past the blocks on youtube at your work or school because some may have higher security blocks on their internet than others.
But first try a VPN or other online web proxy to Unblock Youtube.