if you can provide us with screenshots, it would be helpful in describing your problem.
also, if possible please answer the following questions
1. with your current laptop problem now, are you able to connect to other wireless networks? If yes, is it just one wireless network where you cant connect to? or are all wireless networks a problem now?
(please detail your answers to this first question)
2. lukematts' suggestion is also a good thing to check.
(A) what is the brand and model number of your laptop
(B) what is the brand and model number of your wireless router
3. have you installed or made any changes to the laptop settings/ installed any new drivers or software related to wireless network connection?
4. Your laptop might have Keyboad Function Keys (FN + key combinations) that can turn on/off the wireless adapater inside your laptop. Try pressing the FN+ key combination as shown in your keyboard
5. Your laptop might have a switch/button that can be pressed to manually on/off the wireless adapter inside your laptop. Try pressing this switch if it exists.
hope to hear from your soon, if you can post a screenshot and answer the questions above, we can troubleshoot your wireless problem