extension=php_gd2.dll by .htaccess file

to run captcha i uncommented
extension=php_gd2.dll in php.ini page
but on server i want to make this change by .htaccess file so i made a file
with .htaccess extension and pasted on it
extension=php_gd2.dll
uploaded it on server but this method doesnt work
kindly help me to make this uncomment change
on .htaccess file

Hey.

That is not possible. Enabling extensions is restricted to the php.ini file. (See the manual)

It is possible to use the dl() function, but it has severe limitations. - Most notably, it is not available when running PHP as an Apache module, and even when running in CGI mode it is usually disabled for security reasons.

so should i contact server administrator to do this change only in php.ini .are they able to do this change and restart the server????????

Yes, the server admin will be able to do this.

I am a little surprised that your setup has GD disabled in the first place. It's usually considered one of the code PHP extensions that you can assume hosts support (kind of like the MySQL extensions).

thanx for ur valuable suggestion