Computer screen is broken I'm trying to hook up my computer to my tv via hdmi cable connection.
My guess is that the computer OS (Windows?) is set to 'Show only on 1' by default. This means you have to find some way to access the OS to change the setting to 'Duplicate these displays'. If your screen is broken, you can't access the BIOS menu either, so you're going to have to replace the computer screen.
Have you scrolled through all the input slots on the TV on-screen menu? You might be so insanely lucky that the computer setting is actually set to 'Duplicate' (by chance/mistake) and all you have to do is to locate the one TV input slot that will give you signals. Some TVs feature a dedicated PC or Computer input slot - but I admit it's a long shot.