I accidentally saved the wrong password over the correct password in my iCloud keychain. I don't know the original password I had stored, so now I can't access the account. Can I retrieve an old stored password after I have stored a new password over it?

Yes as posted

Do you use Time Machine and have a backup on hand?

If so, restore an older copy of your keychain from ~/Library/Keychains or just search for "Keychain" in TM.

Other than that you have to use the forgot password - If you forgot your Apple ID password - Apple Support

LN

Do you use Time Machine and have a backup on hand?

If so, restore an older copy of your keychain from ~/Library/Keychains or just search for "Keychain" in TM.

Any solution till now?