Laptop keeps disconnecting from Network

I have internet on main computer, but have lost internet connection to my lap top and my daughter's, how can I reconnect, has anyone any suggestions please?

Call your ISP. There's a 1000 things that could be causing the problem and you've not given us many details to work with. Odds are it's something minor like your neighbor just installed a new wireless router and your laptops are trying to connect to their wifi w/o SSID info instead of your own. Either way trying to troubleshoot via forum is a tedious task and is best accomplished when you have real-time communication.

As a real quick kind of catch-all solution that works from time to time, you can always reset your router and see if your laptops get back on track.