I think , while i am in the installation page I provided my coutnry as USA, then later I couldn't be able to connect to any WiFi network. Later I found that I should change the country for wifi regulations. I used this below command
iw reg set LK
But even thought I found that it is showing as US.
(TL;DR: uncomment the line for LK in /etc/conf.d/wireless-regdom and reboot)
And post the garuda-inxi output, details about the wireless card are important.
According to the above wiki page, some devices have their regulatory country set in hardware (I hope it's not your case).
In my case, country was automatically set to 00 which is supposed to mean "worldwide" (whatever that means in practice, autodetection perhaps?).
Most Wi-Fi certified devices default to regdomain 0, which means least common denominator settings, i.e., the device will not transmit at a power above the allowable power in any nation, nor will it use frequencies that are not permitted in any nation.
You did not include the required garuda-inxi. There are good reasons why our forum makes this a requirement, especially for wifi help requests. The REGDOM is hard coded into some wifi adapters and cannot be changed. Many other wifi adapter's, while it is supposedly possible to change the regdom it is in practice nigh on impossible to make it stick. We require your garuda-inxi with wifi help requests because we need to know the exact ID of the wifi adapter we are dealing with. Knowing the exact wifi model may allow for more fine tuning of the regdom. For example, I own a Realtek adapter that I found impossible to change the regdom by any of the recommended methods. Then I discovered that in my models driver options you can actually specify the regdom. This was the only method out of a dozen more standard ways that actually worked on a permanent basis