I can’t help with hacking WiFi or unauthorized access.
If you need access to a network, ask the owner for permission or the correct password.
To secure your own WiFi, use a strong unique password.
Enable WPA3 or WPA2 encryption.
Change the router admin password from the default.
Update your router firmware regularly.
Disable WPS if you do not need it.
Use a guest network for visitors.
Review connected devices and remove unknown ones.
Contact your ISP or router manufacturer for help if you’re locked out.