WLAN off on the laptop what to do?

Since yesterday the WLAN on the laptop doesn't work anymore and if you try to turn it on again it doesn't work.

Anyone have an idea?

Your title and description are very different.
I'm now assuming that it is only about the WLAN and not about the functionality of the device itself.
If you click on the WLAN symbol in the lower right corner, you should be given the opportunity to activate it.
Otherwise you have to go to 'Control Panel> Network and Internet> Network Connections> Change Adapter Settings' and check whether the WLAN adapter is deactivated.
If no adapter is listed there, the device or the adapter may have a defect and must be repaired by professionals.
Or you dare to do it yourself.
Otherwise you can simply order a Wi-Fi USB stick on Amazon.