Can I upgrade a itouch IOS 4.2.1 to a newer IOS
Depends on which ipod touch.
2nd gen can only go to 4.2.1
If it's a second generation iPod touch, no.
Apple didn't upgrade the 8GB model's hardware when it released the third generation ones.
If it's a fourth generation iPod touch, yes.
You never told us exactly what model iTouch you have but guessing from your question I would bet it is to old to upgrade beyond 4.2.1
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