My screen suddenly became all black. The touch sound still happens, but nothing comes onto the screen. I was thinking of doing a reflash. Is reflashing a possibility at fixing it, and if not what should I do?

Thanks

try your tv out cable (or x11vnc) to at least backup your data first.
tbh, i doubt reflash will help... i think it's something with your hardware. not to say you shouldn't try flashing.
good luck

I experienced similar a few times and reboot resolved it. Somehow hildon stuff crashed and did not restart properly. But your problem might be somehow different.
Do you have backup menu installed? If so booting into it and doing a backup, including saving backup to PC might be good thing to do, given display isn't completely broken.

A reflash didn't work Any place I can grab a replacement screen?

could also be broken or torn ribbon, especially if you can still make calls

Most cell phone markets where they do repairs will probably have one available. Failing that you could always try ebay or just type "N900 replacement LCD screen" and find a decent looking retailer. Expect to pay between $50 and $80 USD for a new one though.