My internet gets lost if I Left my laptop alone. To fix this problem I even tried to switch on and off airplane mode then all my exciting WIFI connection are gone. I need to restarted my laptop to bring back missing wifi connection. Is it windows issue or something else, I'm currently using Windows 10 inside my laptop.
Go to command and try:
ipconfig /release and then ipconfig /renew
If it fails
I'm sorry if its not a big help but we need more info on what's really happening and how.
EG: Is all the WiFi's gone or if you can't just connect back.
It could also be a power setting making it sleep and when it tries to wake up, it fails.
If you find that the wireless card built into your laptop is failing (do other testing like @johnnyenglish suggests), you can buy a USB wireless adapter and plug that into the USB port on the side of your laptop.
Don't remember after which patch but on Windows 10 it was common issue, especially when you keep system online for days/multiple sleep. What I tried for fix without reboot is below.
* ipconfig /release
* ipconfig /renew
* ipconfig /flushdns
If in worst case if doesn't work, try if working after wifi router reset. Flushdns helps when switching between network/vpn.