Well, this does not happen to everyone who uses the internet but only to certain people.
If you happen to lost your internet coincidentally after the 9th of July 2012, it is very likely that your computer is hit with the DNSChanger malware.
Take out your smartphone, tablet or whatever that can go to the internet and try to browse any website. If you are not able to surf from there, chances that you are safe is pretty high because it might be your ISP that is down. Give a call to them to check that out.
However, if your other internet-enabled device can surf to the internet, very high chance that your computer is infected.
So, what can you do?
Happy browsing after this!