Cant open injectors

hey guys another player in need of your help.

as i open the injector i get an error. (im not a total newbie, yes it is extracted >.<)

'to run this application, you first must install one of the following versions of the .NET framework:
v4.0.40419'

i have gone and searched this and downloaded the setup files for Microsoft .NET Framework 4 (standalone installer). my problem here is that i cant run the installer as it comes up with 'Choose the program you want to use to open this file:'

any ideas how to bypass this and download .NET Framework 4 with a program i currently have?

thanks in advance for helpful replies