PLEASE LET IT BE KNOWN, IF YOU USE ANY OF THESE PROCEDURES YOU DO SO AT YOUR OWN RISK.
If your ipone/touch crashes and gets stuck on boot screen what do I do??
First bring up iTunes to see if it sees your device, if so you will need to do a restore.
If not you will need to go into DFU mode. DFU mode is a state that you can put your iPhone into where it can interface with iTunes but does not load the iPhone operating system or boot loader (this is what really differs DFU mode from recovery mode). DFU stands for Device Firmware Update
How do you get into DFU?
In the case of a crash where iTunes does not see your device,keep iTunes up but disconnect your device from teh computer. Then hold power button down till screen goes black. You can now reconnect you device to computer. Now to get into DFU mode.
1. Make sure your phone is off (black screen) Push down power button for about 3 seconds.
2. While holding power button down press and hold the home button down, wait exactly 10 seconds.
3. After 10 seconds release the power button, but do NOT release the home button untill you see that iTunes sees your device, this usually takes about 30 seconds.
4. Once iTunes sees your device you can let go of the home button. (If more than a minute goes by and iTunes does not see your device, then you are most likely are not in DFU mode. Repeat steps 1 through 4 again. Some times if your timing is off on button hold down times it may not go into DFU mode, it might take a couple of tries to get it.)
5. Now you will be able to Reload your device through iTunes to original settings and configurations.
On iphone if you have a valid sim card you will be able to restore your settings if you had saved them in iTunes. If you do not have a valid sim card you will need to unlock and jail break your phone to be able to get back in. Below is a post I did on jail breaking, if you do not how to do this it will help you out.