how do i cast laptop to tv without losing anything?

If picture goes over fine but the sound stays on the laptop speakers, click the speaker icon in the taskbar and pick the TV as the output. Windows doesn't always switch it over on its own, especially the first time you plug in.

If you mean without losing picture or sound quality, a plain HDMI cable beats every wireless option. Laptop into the TV, pick that HDMI input on the TV remote, done. Sound goes over the same cable. If your laptop only has USB-C, check it supports video out before buying an adapter, not all ports do. Wireless works but it's a compromise. On Windows, Win + K brings up the Cast panel and will find a TV that supports Miracast. Chrome can also cast a tab to a Chromecast or Google TV from the three-dot menu. Both are fine for a film, laggy for anything interactive. One more thing: press Win + P and choose Duplicate if you want the TV to mirror the laptop. Extend puts the TV as a second screen, which is where people "lose" their windows.