Maybe the remote control has malfunctioned, or its batteries are worn out. Try pressing the physical buttons, located on the device. If you are able to switch channels, the remote control was the reason why you couldn't switch channels in the first place.
Check out the solutions to remote control doesn't work, to learn how to make the remote control work again.
Try turning off the TV and turning it back on after a few minutes. Also, you can unplug it from the power outlet and plug it back in after a few minutes. By doing this, you will restart the TV's hardware and possibly resolve this issue.
The device's IR sensor receives the instructions you send to it using your remote control. If you have put any object over the device's IR sensor, make sure to remove it as the IR sensor won't be able to detect the instructions sent by the remote control. Usually, the sensors are around the logo, next to the stand-by light, or in the lower, right part of the device.
If you can't switch channels on your TV and you are not sure what to do, contact Toshiba's customer support team, which you can get in touch with by dialling the following number: +1 800-457-7777.
If you didn't manage to contact them by dialling the above-mentioned number, you can do that online on their website (click here to visit it).
If you don’t receive the email in the next 2 minutes please check your junk folder, and add [email protected] to your safe sender list.