I tried to do full compatible analog of javascript's encodeURIComponent for c# and after my 4 hour experiments I found this
c# CODE:
string a = "!@#$%^&*()_+ some text here ??? ??????? ????";
a = System.Web.HttpUtility.UrlEncode(a);
a = a.Replace("+", "%20");
the result is: !%40%23%24%25%5e%26*()_%2b%20some%20text%20here%20%d0%b0%d0%bb%d0%b8%20%d0%bc%d0%b0%d0%bc%d0%b5%d0%b4%d0%be%d0%b2%20%d0%b1%d0%b0%d0%ba%d1%83
After you decode It with Javascript's decodeURLComponent();
you will get this: !@#$%^&*()_+ some text here ??? ??????? ????
Thank You for attention