How do you mean "My PC isn't supporting".
By the way, why do you need 4.0?
I want to install .Net Framework 4.0 but my pc isn't supporting any version of the .Net framework below 4.5 which was built in(supports 4.6). I spent weeks reading and finding my solution in different forums but all the solutions are like they had older versions of framework like 3.5 and were having problems installing 4.0 and a solution caught my eyes in this forum which suggested to install .Net framework 4 client profile first and then to install framework 4. The question maker had his solution then (question was made in 2011) and i followed the same but did't for my case. Any solution?