a network cable is unplugged

Hi, i dont now alot about computers and have a problem that im hoping someone can help me with. I have recently bought an acer one note book, after a few weeks of it working fine, it now all of a sudden has a bubble saying a network cable in unplugged. I usually connect toa wireless belkin router and my other laptop is still connecting to this router fine! There in a switch on the front of the acer for wireless which i have switched on and off, i have also gone into networkss and disabled and enabled, and reset both the router and modem but still nothing. Can anybody help? Thanks 🙂