Need some help about proxy/internet settings

I am using mozila firefox for browsing internet.
2 days ago when i was trying to open any website then mozila give me this msg.
The proxy server is refusing connections
Firefox is configured to use a proxy server that is refusing connections.
Check the proxy settings to make sure that they are correct.
Contact your network administrator to make sure the proxy server is
working.
And when i change some settings about proxy in mozila then i can able to open all websites except “facebook”.
When ever i try to open facebook its give me this msg after 20 to 30 seconds.
The connection has timed out
The server at www.facebook.com is taking too long to respond.
The site could be temporarily unavailable or too busy. Try again in a few
moments.
If you are unable to load any pages, check your computer's network
connection.
If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.
Please help me out. i am really tired of this now.
Thanks
Answer #1
Is this machine in a school/work related environment? Or are you using your own device at home?
If it’s the first, try this: warpproxy.com/
If it’s your own pc, on your own network.. scan for malware and reset your proxy settings like this:
You can find the connection settings in Tools > Options > Advanced : Network : Connection
If you do not need to use a proxy to connect to internet then select No Proxy
Answer #2
another site proxynova.com
it’s better to use elite proxies