urgent help needed :(

Try NVRAM reset:

• Shut down your Mac.
• Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
• Turn on the computer.
• Press and hold the Command-Option-P-R keys before the gray screen appears.
• Hold the keys down until the computer restarts and you hear the startup sound for the third time.
• Release the keys.

Shown here - there are two. It is also labelled Alt on some keyboards.

The two keys that are between the option keys and the space bar are both command.

For command and option, you can use the two keys to the left of the space bar, or the keys to the right. They function identically.

First of all, your Mac will always think there are two displays, because there are. The fact that one cannot show anything does not change that.

The first thing you want to try is to get the Mac to ignore the built in screen. After you boot up, close the lid of the laptop. That usually tells the Mac you want only the external monitor, and the TV will become the only display.

That should switch the main display to the TV. You will need a mouse to do the rest since your keyboard and trackpad are now not available.

Go to Apple menu / System Preferences / Displays. On the TV click Scaled. You will see the resolutions that can be displayed on that screen. Select a set of numbers above whatever is selected now and try it. You can keep switching the resolution until you find what you like.

If that works, and you want to keep using your laptop this way, get a keyboard and a mouse and keep the laptop closed.