Q: Itunes is not restoring and updating iphone 5 on ios 8.2...it shows error 3914 plz help me....

Hey Jalilwaqar45,

If you are constantly getting that error 3914 when restoring, take a look at the article below. The best way to get it sorted out is to restore your iPhone on a different user or on a different computer all together. 

Error 3194, Error 17, or "This device isn't eligible for the requested build"

https://support.apple.com/en-us/HT201442

Take care,

-Norm G.