You can try Dreamhost's free web based FTP client
. Be forewarned that you are sharing your authentication details with the website and it's not recommended until you have exhausted all other options. More info on it here
You can also set up net2ftp
, a hosted FTP client on your server and use it to FTP into your server. This is a relatively less risky thing to do since the software in it's vanilla form does not store passwords, and even if it did it will be stored on your server, which you can remove by simply deleting the net2ftp folder.