Please help my 804s tweeters are not working

Have you clipped the speaker by driving them with almost all of the amps power? That's the main reason the tweeters go in most speakers.
If not, did you buy them new? if so send them back for repair.
If they are not under warrantee, pull the tweeter out of the cabinet and make sure everything is hooked up.
Could also be a bad crossover.
Good luck.

Make sure the bowie jumpers are installed correctly.

Yeah I probally clipped the speaker. I have driven them under about 80-85% power. What does that mean and doest that mean they need to be replaced.
How can i find out if the crossover is blown and how to replace it.

85% is clipping territory for sure. Yes, you will need to replace the
tweeters. Clipping happens when a amp runs out of power and starts
distorting . This distortion cooks the tweeters. If you need to play at the
volumes that clipped the tweeter, you should get a amp with more power to
drive the speakers with out running out of power.
Hope this helps. I've clipped tweeters before I learned how not to do it.

Yep, tweeters are usually more vulnerable than other speaker drivers. Woofers are usually blown when speaker is overpowered and played loud or destroyed by analogue LF rumble.
Crossover will less-likely be affected.