Is it possible to find the Wi-Fi password from your iPhone without jailbreaking it?

I have forgotten my Wi-Fi password and I only have it stored on my iPhone. Is there anyway of finding it out without jailbreaking.

Nope!

Probably not and even if there's a way I think it'd be much more complicate that the simple fact that you should just reset your router and give it a new password.

To reset the router, straighten a paper-clip then stick it in the reset button on the back of the router and hold it down for a couple seconds.It'd be reset back to factory setting. Read the manual to learn how to assign password. For simplicity, just hook your computer to the router with an ethernet cable. Click start>cmd> ipconfig > note the default gateway number (e.g 192.168.1.1), bring up a browser then type that string of number the browser; it will ask for the admin password. Consult the manual or look up online for the password to access the config page. Once you get in, utilize common sense to set password to your wi-fi.

No not at all but jailbreak it and there's about 10 cydia apps you can get. Just jailbreak and find out your passoword then un-jailbreak if your so desperate.
Or reset your router to factory setting but thats annoying and sometimes doesn't work. Just depends on the router. You have to use a paper clip and there will be a tiny winy little hole just stick it in for 10 mins and done. Be careful with that option though. Search your brain for the password. Search Really hard!

1. Firstly, get the default gateway
XP
Goto Start/Run
Type in "cmd"

Vista
Click the Start button
Type in "command"

Once you are in the command prompt:
Type in "ipconfig", get the default gateway info (eg: 192.168.1.1)

2. Log into your router, and set up the password there.
Type your default gateway in your Internet browser (eg: http://192.168.1.1)
Login (search online for login info) Usually admin, password
There should be a link on the side somewhere for you to set up the password.