我创建的子域网址在我的网站，但它总是显示找不到网页的错误。当我写 foldername.website.com 所以它显示找不到网页，但它的工作原理，当我写 website.com/foldername 。我已删除的主文件夹和子文件夹，但还是子域网址的.htaccess所有code是行不通的。

您的网页文件夹的设计应该是这样的：

website.com

  /＆LT;根＆GT; -----＆GT; ＆LT;对于网站＆GT的内容;
 

forum.website.com

  /＆LT;根＆GT; --------＆GT; ＆LT;对于子域名网站＆GT的内容;
 

您真的不能有这两个文件夹的嵌套关系，就像网站的文件夹不能包含的子域文件夹;这看起来是这里的情况

I've created sub-domain URL on my site but it always shows "page not found" error. When I write foldername.website.com so it shows page not found but it works when I write website.com/foldername. I've removed all code of .htaccess from main folder and sub folder but still sub-domain URL is not working.

Your web folder design should be something like:

website.com

/ <root> -----> <content for website>

forum.website.com

/ <root> --------> <Content for subdomain website>

You really can not have a nested relationship for these two folders, like website folder cannot contain the subdomain folder; which looks to be the case here.