I'm afraid you will have to provide more details if you want help - a number of issues may be involed.
Well check the obvious first... Is your internet up? Are the user account and password up to date? Can you use your online hosts FTP facility and not just the Filezilla ftp? There are other details you need to point to to get specific help...
Check the OPs other threads. He is new to all of this. I suspect that your hosting account isn't set up properly. If you can sort that out then Filezilla should work. What specific error message are you getting in Filezilla? Note that your FTP password may not be the same as your Hostgator account password.
Well, i support what killerdesign said...! Recheck everything, your net connection, FTP hostname, ID and pass, port no. etc...! Correct incase if anyone of these were wrong and just try to reconnect...! it will be alright..!
If your a mac user, use this: http://www.panic.com/transmit/ It's all about the drag'n drop. Extremely easy to use compared to the Windows FTPs out there. I just could not believe how you Windows users know how to use this: http://filezilla-project.org/images/screenshots/fz3_win_main.png