Completely broke my site

Hi,

I tried to update this plugin and now my website is completely broken. Getting the white screen of death on the front end, and the error

“ERROR: The themes directory is either empty or doesn’t exist. Please check your installation.”

in the admin section. Also it said all of my plugin files are missing.

Additionally, it seems my FTP has been hijacked as I keep getting “permission denied” errors when I try to access the /plugins/ or /themes/ folder

HELP!!

https://www.ads-software.com/extend/plugins/w3-total-cache/