wireless internet access problem – lenovo T 61p lap top

wireless internet was normally functioning , but suddently one day i was unable to access internet, the wireless settings and internet settings and network settings are all checked and compared with my colleque system, seems to same and shows proper settings, but whennever i try to open any web page it will show “the page cannot be displayed”.my lap top is lenovo T61P ThinkPad series…….please provide me a solution