I didn't attend the Biometrics appointment for personal reasons, so I got refusal letter and I sent a message to them explain my reason but they said the final decision is made and you can't do anything, and now I'm planning to apply for the UK visa and on my application they ask me if I was refused from any country, what I should do about that? is there any impact on UK visa application result?
You should answer the questions on your UK application truthfully. i.e. Answer that you were refused a Canadian visa. There will be space somewhere in the application form for you to explain your reasons. If not, add a covering letter with the explanation.
This may have an effect on your UK application, or it may not. It depends on the reasons you have for missing the biometrics appointment and how you present them.