I want to inactive selecting & copying text in html page. when I used Javascript & inactive right click user can use Ctrl+V!!
There is no full proof solution. You can play javascript games (easy to turn off). You can place invisible layers about the text so it can't be selected easily (easy to view source). You can use images instead of text (just bad).
You can't. Don't even try. Don't annoy your users.
If you put it publicly on the web, it can be copied. Technically, it already is copied as soon as the user sees it. As colithium pointed out, all the techniques can be circumvented. Heck, you can look at the source code. You can curl the raw data from the command line, no JS/IMG/layer hack can prevent that.
While I agree in principle with the other posters that trying to do this may annoy the user, sometimes a manager or customer demands that this be done, and so an answer needs to be supplied.
Check out this page on www.dynamicdrive.com that will supply you with a few JavaScripts towards this end. Specifically see "Disable Text Select Script" and "No right click script".