Im unable to reinstall adobe fash on my laptop, the issue remains unclear to me

I have a pc with windows vista basic, the browser is firefox, the version im unsure off but i know it has to be updated. (an underlying problem is that my HDD has limited capacity) so updates being carried automatically sometimes are a problem. i actually removed the adobe flash from my list of plug ins as it was no longer working ( it had failed to be upgraded) i done this in the hope of generating extra HDD space, once i had freed up enough space, reinstalling abobe flash wont carry out, each time it will only go to my download folder/ location and it will not respond to me after that i.e i cant complete the installation, i have cleared HDD space to reinstall but it fails each time, i have also tried to upgrade firefox but it also fails in a similar way to adobe flash

Any feedback would be appreciated