電腦上唔到網....!!!!!! help me pls

我部電腦唔知做咩上唔到網,,,我用網上行....屋企有三部電腦一齊用...其中有兩部電腦可以同時上網...
但我想連線時...禁左連線個制之後,,佢冇反應...之後出現"撥號錯誤"個d....但我d上網密碼冇改過..用左好耐...
佢又唔似中毒...速度正常....
我唔想洗機....咁點算好...!!
thank you very much...