my ipod 4th gen doesnot charge

If this shuffle is brand new, make sure the plug on the docking cable is completely inserted into shuffle's headphones jack, as shown in this document

http://support.apple.com/kb/ts3572

Otherwise, if the shuffle's power switch has been ON since the problem occurred, do this to Reset the shuffle

http://support.apple.com/kb/ht1655

If you tried it on your computer's USB port and also a USB power adapter, you have probably ruled out a problem with the USB port not supplying enough power. However, be sure to try it on the computer, after shutting down (powering off) and restarting the computer, with other USB devices disconnected (except for standard keyboard/mouse if used).

Since you get at least the red light, the USB docking cable is probably OK. And if you have ruled out the USB port and USB docking cable, the likely cause is the iPod itself.

When connected to the USB port on computer, does it still appear in iTunes? If it does, you can try doing a Restore on the shuffle. The Restore button is on the shuffle's Summary screen in iTunes.

If you have ruled out a problem on the USB port and a docking faulty cable, the cause is likely to be on your shuffle.

If it's less than one year from purchase date, it is under warranty. If there's an Apple Store nearby, you can make a reservation at the store's Genius Bar to have to checked (whether it's under warranty or not). Be sure to take your USB docking cable, and if your computer is a laptop, you may want to take it along as well.