Plugins were working fine, now they're not

I’ve been using WP on my blog for awhile and had several plugins installed and working fine. I upgraded to 3.0.4 and now none of my plugins show up in the dashboard. They are uploaded, unzipped, not in nested folders, and I can view them via FTP but can’t activate them or even see them.

I’ve searched through the forum and found others having the same problem, but no fix that works for me.

I’ve changed to the default theme – no change. So I changed back to my theme. I’ve wondered about permissions, but don’t know what to change without messing something up.

My url is https://darlenebishop.com – can someone help? Please? Pretty please? Thank you! ;o)