一般在安装PHP时都很少启用 mcrypt 扩展，所以在使用 phpmyadmin 时会提法“无法载入mcrypt扩展”的信息，解决的办法：
1、打开php的配置文件“php.ini”文件
找到 “;extension=php_mcrypt.dll”和找到“;extension=php_mbstring.dll”，去掉前面的分号“;"”，把前面的分号去掉。
要是不行就多开启一些扩展dll文件，如：
extension=php_bz2.dll
extension=php_curl.dll
extension=php_dba.dll
extension=php_dbase.dll
extension=php_exif.dll
extension=php_fdf.dll
extension=php_gd2.dll
extension=php_gettext.dll
extension=php_gmp.dll
;extension=php_ifx.dll
extension=php_imap.dll
extension=php_interbase.dll
extension=php_ldap.dll
extension=php_mbstring.dll
extension=php_mcrypt.dll
extension=php_mhash.dll
extension=php_mime_magic.dll
extension=php_ming.dll
extension=php_msql.dll
extension=php_mssql.dll
extension=php_mysql.dll
extension=php_mysqli.dll
extension=php_oci8.dll
extension=php_openssl.dll
extension=php_pdo.dll
extension=php_pdo_firebird.dll
extension=php_pdo_mssql.dll
extension=php_pdo_mysql.dll
extension=php_pdo_oci.dll
;extension=php_pdo_oci8.dll
extension=php_pdo_odbc.dll
extension=php_pdo_pgsql.dll
extension=php_pdo_sqlite.dll
extension=php_pgsql.dll
extension=php_pspell.dll
extension=php_shmop.dll
extension=php_snmp.dll
extension=php_soap.dll
extension=php_sockets.dll
extension=php_sqlite.dll
;extension=php_sybase_ct.dll
extension=php_tidy.dll
extension=php_xmlrpc.dll
extension=php_xsl.dll
extension=php_zip.dll
2、重启 apache 或者 IIS 即可
如果还不行，就在 PHP 的安装目录下面找到 libmcrypt.dll ，把它复制到“C:\windows\system32”面，再重启