note 82480 deleted from function.sha1 by nlopess

Note Submitter: Andy ---- How do you undo a SHA1(), I've used this function to "encrypt" a password, but let's say the user forget's their password, if I e-mail it to them then they will get a weird set of numbers that will not work when they want to log in, so how do I reverse a SHA1() function, or is it possible? If not could someone please tell me an alternative to this, something simple please I'm only thirteen and programming a huge website.