Decrypt Membership Hashed password saved in Database

Hi

I have a database of old developer, who left the team, he was using the Asp.net Membership for User Registration and for userLogin.

all password are saved in aspnet_Membership table in Hashed Encrypted format.

I want to change the database structure , so i need to get all user password in plain text.

I applied so many methods for decrypting the password but no success.  my web.config have this configuration.

<add name="AspNetSqlMembershipProvider"  type="System.Web.Security.SqlMembershipProvider,System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" connectionStringName="MainConnectionString"
             enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false"
             applicationName="ibuy" requiresUniqueEmail="true" passwordFormat="Hashed" maxInvalidPasswordAttempts="5"
             minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10"
             passwordStrengthRegularExpression=""/>

one user sample of pasword in Database table aspnet_Membership saved like this :

Password : Lg+Jnl/V35eL9Is60b26B461Yns= 

PasswordSalt :  vSPpxkr7vsNwec507y169g==

please help .