The ribbon cable can be replaced, review this guide Macintosh PowerBook 165c Display Replacement
Are you sure the issue is the ribbon cable? This series used CCFLs to light up the LCD screen, I’m suspecting that’s the real issue as it was quite common.
Take a flashlight pressed on the screen at an angle do you see a faint image of your desktop icons? If you do the backlight circuit will need to be checked out as well as the CCFL lamps.
Here’s one source for parts TheBookYard - PowerBook 165c
As far as connecting an external display, that is possible! Your system offers a mini DB15 connector. You’ll need a special adapter cable to convert to VGA or composite video
Review the EveryMac specs for this system here PowerBook 165c Specs