If you can't download files from the Internet using your browser, press the Alt key and from the Tools menu select the first option (Delete browsing history). After that, use the opened window to delete all cookies, cache and temporary Internet files. If it doesn't help, try resetting the Internet Explorer configurations. Alternatively, you can check Software Informer database for another browser.
Note: If you need to download large files, I suggest you use a download manager to increase the downloading speed.