There are times when you might face this unusual issue on a windows pc when windows laptop is no longer getting connected to the wifi network, it really strange but it happens at such point of time you can take different ways to solve this problem but before you read about these method you should know that this issue can be solved most of the time just by restarting your laptop.
If you want to know the reasons you should know that it could happen due to fault or conflict in the drivers for the wifi adaptor, now firstly check for the drivers issue and if that is true then you should re install the drivers for the wifi and the problem should get fixed.
Check to See If Wifi Adaptor is Disabled
Go to control panel >> open Network and Sharing Center and the select network adapters in the left pane and then disable or enable if the wifi adaptor is already disabled and then check to see if the issue gets fixed.
Login with a Different User Account
Try login with a different user account on windows, if it is a single account pc or laptop you should create a new account and test it after then, it may sound strange but this may fix the issue as it worked for many other users out there.
Try Wireless Troubleshooter With in Windows.
In case if the wireless connectivity issue is not solved by above method you can try fix in built in windows to fix this issue by running the troubleshooter which will tell you the possible reasons to fix this.