You can use pretty much any router with any operating system.
Read or download the manual for your present router.
If the password to enter the router setup screens has been changed
you can reset the router to defaults by pressing the reset button (usually on the same panel as the sockets and behind a pinhole).
Once in the router setup screens go to wireless security and review or renew wireless security type and passphrase (if any) and apply to computer's wireless adapter user interface or to Windows Wireless Connection screen.