No HTML/Visual mode option in admin panel (New Post)

Turn off all your plugins… then check it. if its all good
(what would probably be true) start activating your plugins
on at a time to find the problem maker.

This happened to me several times and in 9/10 cases was a plugin…

the 1/10 time was a nasty code i pasted into my functions.php so if
turning off your plugins doesn’t work activate error report temporary

by changing:

define('WP_DEBUG', false);

To:

define('WP_DEBUG', true);

And paste in your questions the error or if you can fix them
and the try again…

Hope this helps 😉
Cheers, Sagive.