There is no single "magic" Google Sites unblocker. The best method depends on your specific situation.
If you cannot install software, web proxies are a fast solution. These sites allow you to browse the web through their servers. google sites unblocker
Preventing access to inappropriate material in restricted environments. There is no single "magic" Google Sites unblocker
Below is an overview of how these work, the risks involved, and how to troubleshoot access issues. 1. Using Google Sites as a Proxy (The "Unblocker" Site) the risks involved