Plugins don’t show up in dashboard (folders are NOT nested!)

I recently had to start over from a backup after my site was hacked. I also upgraded to 2.6. I tried reinstalling all my plugins (maybe 5 or 6 total), but the only ones that showed up were akismet, no self-ping, and get recent comments.I double-checked my plugins folder, and none of the folders are nested (ie, I uploaded the correct folder, not the folder containing the correct folder).

Any suggestions?

Thanks.