Skype, Gmail and facebook can not open!1

Hello,

Pleas help me I'm stack. My laptop just stoped allowing me to open face book, gmail and skpe I dont know what ahappened. Otherwise, all other sites are workinig very well. when I try to open it just tells me about my connections of which that is not true because my internate is working and connected and I do open other sites . its only these three pleas.. help if you can.,..