plugins missing headers & gzuncompress errors

I login to my WP as the admin to check for plugin updates and I got the error that all my plugin’s are missing headers and they all was deactivated.And they dont’ show up on the installed page. I ftp ina dn see them there but WP doesn’t see them @ all. Also got
Warning: gzuncompress() [function.gzuncompress]: data error in /*******/*********/******/wp-includes/http.php on line 1824