was on a website when I got a message asking what I wanted to open the application with and I told it Firefox and now it won't open at all.
Was on a website when a box opened up asking me what I wanted to run the application as and I clicked on Firefox - now I can't use that website.
Wšykne wótegrona (1)
You should never select Firefox as the application to handle a file if you get an open with dialog.
Firefox wouldn't ask this if it can handle the file.
You will have to remove that action in Tools > Options > Applications
See also: