I was having same kind of problem with ldap, intl, curl php extensions. I've solved those issues by the following ways:
At first you've to check whether these extensions have been enabled in the php.ini file by removing semicolon (;) in front of the following lines:
;extension=php_intl.dll
;extension=php_ldap.dll
;extension=php_curl.dll
Secondly, libeay32.dll, ibssh2.dll and ssleay32.dll files have to be loaded by php properly to function those extensions properly. These dll files are required by several php extensions (ie curl, ldap, intl etc). These files generally reside in the php installation directory [for my case it is C:\php directory].
Additionally, for intl extension to be enabled you're gonna need some other dll files to be loaded by php properly. The name of these files begin with icu (ie icudt57.dll icuin57.dll etc for php version 5.6). You'll also find these files in the php main installation directory.
There is a alternate way you can load these files from your httpd.conf (apache configuratio file) file instead of copying them to the apache's bin directory. This can be done by using the following technique:
Please note that my php version is 5.5.
LoadFile "C:/php/icudt51.dll"
LoadFile "C:/php/icuin51.dll"
LoadFile "C:/php/icuio51.dll"
LoadFile "C:/php/icule51.dll"
LoadFile "C:/php/iculx51.dll"
LoadFile "C:/php/icutest51.dll"
LoadFile "C:/php/icutu51.dll"
LoadFile "C:/php/icuuc51.dll"
LoadFile "C:/php/libeay32.dll"
LoadFile "C:/php/libssh2.dll"
LoadFile "C:/php/ssleay32.dll"
That's it.