I remember the times when TVs had buttons that mimic all the remotr functions hidden behind some door on their body. Made things easier for times you lost the remote.Find your remote, or get a new remote.
If you’re plugging a Chromecast into an HDMI port, then casting to it will probably switch the TV to that input, provided you have HDMI-CEC enabled.
But you still need a remote to switch back to broadcast/cable TV.
I remember the times when TVs had buttons that mimic all the remotr functions hidden behind some door on their body. Made things easier for times you lost the remote.