Go to your wifi settings and make sure the "Ask to join networks" button shows ON. with this, it will automatically join wifi networks it has previously connected to.
If this doesn't solve the problem, make sure you are close enough to the wifi source. Venturing too far away from the wifi will make you loose connection.
Does the iPod connect to other networks OK? If so that indicates a problem with yuor networ. Maybe time for a new router.
Does the iPod see the network?
Any error messages?
Do other devices now connect OK?
Did the iPod connect OK before?
Try the following to rule out a software problem:
- Reset the iOS device. Nothing will be lost
Reset iOS device: Hold down the On/Off button and the Home button at the same time for at
least ten seconds, until the Apple logo appears.
- Power off and then back on the router
- Reset network settings: Settings>General>Reset>Reset Network Settings
- Restore from backup. See:
- Restore to factory settings/new iOS device.
If still problem make an appointment at the Genius Bar of an Apple store since it appears you have a hardware problem.