No internet - Proxy Settings?

[Natasha]

I'm trying to use internet explorer (Google chrome's saying the same too) but it's coming up with this,

The proxy server isn't responding

•Check your proxy settings. Go to Tools > Internet Options > Connections. If you are on a LAN, click "LAN settings".
•Make sure your firewall settings aren't blocking your web access.
•Ask your system administrator for help.

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It was doing the same on Firefox, but i somehow managed to fix that, but i still can't access the internet on explorer or chrome, any help?
Forgot to mention that this laptop is my own, It's worked perfectly for a year and half and then I came across this problem quite randomly. But I bought it for my uni work last year, it's not actually left the house