No internet error in laptop

Hi guys,

My tp link router is giving a weird issue with our laptop. It was working fine but since yesterday afternoon whenever I connect the laptop to the modem it says no internet. There is a yellow sign on the wifi widget in the laptop. The name of my phone's WiFi and password is same that of the router. I share my phones Internet to the laptop whenever there is no electricity. I thought the lappy might have saved the Mac or something else of the phones hardware so I selected forgot password option in the lappy and reentered the password but the same error is there. I am able to connect all devices to the modem so there is no need to reset it. I used the inbuilt windows troubleshooter and it is saying that wifi does not have a valid ip configuration. What should I do?

Thanks