Please provide specific error message, instead of just 'download fails' as that's not descriptive enough to assist. If you can post a screenshot it would be better than just typing the message you're getting (see The specified item was not found.). Also, are you attempting to install Flash Player for Internet Explorer or other browsers?
P.S. I deleted your other thread, The specified item was not found.. Posting the same question in multiple threads doesn't help your question get answered faster and leads to confusion in managing the same question in two threads.