If you use IIS Windows Server add web.config
file in root folder and put the below code :
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="Imported Rule 1" stopProcessing="true">
<match url="^(.*)$" ignoreCase="false" />
<conditions logicalGrouping="MatchAll">
<add input="{URL}" pattern="^system.*" ignoreCase="false" />
</conditions>
<action type="Rewrite" url="/index.php/{R:1}" />
</rule>
<rule name="Imported Rule 2" stopProcessing="true">
<match url="^(.*)$" ignoreCase="false" />
<conditions logicalGrouping="MatchAll">
<add input="{REQUEST_FILENAME}" matchType="IsFile" ignoreCase="false" negate="true" />
<add input="{REQUEST_FILENAME}" matchType="IsDirectory" ignoreCase="false" negate="true" />
<add input="{R:1}" pattern="^(index\.php|images|robots\.txt|css)" ignoreCase="false" negate="true" />
</conditions>
<action type="Rewrite" url="index.php/{R:1}" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>
and if you use .htaccess
use this one :
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]