Plugins all the sudden not showing…

I had a few plugins installed and they were showing up in my dashboard under plugins. Now all the sudden there gone. I checked in my FTP and the files are still there but again, not showing in my dashboard. A few are still there but a few are missing. I am sooo not good with all this coding but I know that I downloaded them correctly, like I said they were there for months! Now nothing. Any suggestions?