I just upgraded to windows 10 home and it come with directx 12 but my graphics card doesn't support it.it only supports directx 11 and under so I need so know how can I get directx 11.with this problem I can't play any games.
Are you asking how to install DirectX onto your machine? if so then you can do so by following this guide. If you're asking how to downgrade to DirectX 11, it's not possible.
DirectX is achieved through both your hardware and your OS. If your hardware supports it but your OS doesn't, you won't be on the latest Direct X version, likewise if your OS supports it but you lack the necessary hardware, you won't be on the latest DirectX revision.
Now, can you list the games that you're trying to run but can't? Have you tried running the games in compatibility mode?