Unable to access admin panel

I was installing wordpress, which worked fine, until I changed something on the Filezilla program. I was uploading files onto Filezilla, and a little later my website had the screen of file error: 500. When I was uploading the Filezilla files I pressed forced quit because my server kept disconnecting, and then re-uploading (using the overwrite option.) which is probably a mistake I know of now. In any case, my website refuses to open to any page, admin. panels and log – in won’t work, and my hosting co. says it was not a prob with the server. Does someone know how to fix the scripting issue? If you do, please explain with lots of detail.