Internet works at home but not at home?

For about 6-7 months my wifi was working fine at work but now it all of a sudden stopped. I started using a Ethernet cable instead of wifi and it works fine but it's a pain because I'm stuck in one room. My wifi works just fine at home but just doesn't at work. It says that signal strength is good but that I have no Internet access. Any ideas on what's wrong/how to fix it.... I've already tried a IP renew and that didn't work