If you are talking about the OpenERP admin user password, you can recover it if your database passwords aren't encrypted. (as for any other OpenERP user password)But I recommend you can follow some related articles like  the The Best Online Available Password Manager For Database: http://www.passwordmanagers.net/The-Best-Online-Available-Password-Manager-For-Database.html.

I believe you can get some free and useful tips about master password recovery.

For the basic protection of Password Manager For Web Database, you can follow to http://www.passwordmanagers.net/Password-Manager-For-Web-Database.html.

Btw, I am using the auth_crypt module so I cannot just simply recover my old password by looking in res_users.

Normally what you do is provide in the clear text section of the database that looks like random text in the password field is a string of random text that matches a password that is known to decode to a known password.

An example in the context of PostgreSQL http://postgresql.1045698.n5.nabble.com/Algorithm-for-generating-md5-encrypted-password-not-found-in-documentation-td4919082.html