Iphone 3GS device locked
I have iphone 3GS purchased in 2010 from Vodafone India with firmware 6.1.3 functioning well until now. Today it rebooted on its own and then message appears connect to itunes. When connected through windows, message on itunes is "itunes cannot read the contents of the iphone "Nika". I do not have back-up of my contents. The itunes is asking to restore but if I restore, my contacts will be lost. When connected through Window, my photos and videos import window opens up which indicates it is possible to read the files on the device. Even the homescreen set by me is visible on the device.
I can restart it in DFU mode too when connected with PC and message appears "iTunes has detected an iphone in recovery mode. You must restore this iphone before it can be used with iTunes." But the problem is that if I restore all contacts will be lost.
When connected with PC in normal mode (i.e. not in DFU mode), the device is turning off and on again and again on its own. However, in DFU mode, this problem is not faced though screen remains dark.
I tried it on Apple Mac also but the problem is same.
Pl suggest a solution either to get into the device storage file to extract contacts or facility to take back-up or restore with back-up of contacts. If nothing is possible, can I jailbreak in the current form, open SSH and get the addressbook.
iPhone 3GS, iOS 6.1.3