Phone gone into water

@ahmedmemon you will have to treat it like any other water damaged device. first and very importantly, you want to stop continuing to try to charge, sync or otherwise use your phone. This potentially can make a bad situation worse.This may further damage your phone.

The next thing to do is to clean it. Disassemble your phone using these guides. Since iFixit does not have guides for this model yet, use those even so they are written in French. Browsers like Edge or Chrome will translate them into a usable format.

You must remove all EMI shields from your boards (motherboard and charging board). If you do not remove those, you might as well not do anything. After you removed those, clean the boards, connectors and all with +90% (greater % if you can get it) isopropyl alcohol. Follow this guide. Even so it was written for an Apple iPhone 3G, all the points are still pertinent to your phone as well. While you clean your board, check for any obvious damage, like burned or missing components etc. When it is properly cleaned, replace the battery. All these steps are to avoid delayed failure caused by corrosion. Best thing to do would be to clean it with an ultrasonic cleaner, but if you do not have access to one, this will at least help. Once all this is done, reassemble your phone and reevaluate. Until it is cleaned, everything will only be a guess. Besides the battery, I would be prepared to replace the charging board as well. Even with all this, water damage has only a small chance to be fully repaired, but at least you can give it a try.