<p>I am storing all my passwords in the form hashed. I need to retrieve these passwords
Eg</p>

<p>My password is "123456" I save this as hashed "3453474852dfdsfdsfdf" value.</p>

<p>I need to retrieve the original password from the hashed value. (Get Password).</p>

<p>How can I do that?. I am doing SHA1 hashing algorithm.</p>

This is not possible. SHA1 is, very carefully and deliberately, a
one-way function
.
Why are you trying to recover the original password? It is not needed for authentication, because you simply hash the input password and compare the hash values.
If it is because the user forgot their password, then standard practice appears to be generating a randomized reset link and emailing it to the user.