My iPhone repairing cost

Aqeel, I'm afraid there's no way for us to answer that question without diagnosing what's burned up on your phone. This site is dedicated to giving you the tools and information needed to repair your own devices so the repair cost would only be the cost of parts you buy yourself.

On the other hand, if you are looking to have someone else repair your phone for you, it will be up to you to find a repair shop that's capable of diagnosing and repairing your phone. Most shops will be able to do a diagnosis for a fee and let you know what it will cost to fix your phone - if possible.

The thing is, a spark and flame is bad. The source of that flame is something we can't know without opening up the phone and examining and possibly testing some parts of the phone. At that point the source could be obvious or it could take some troubleshooting to find.

If you wanted to try to fix your phone yourself I would start with replacing the battery and the charging port then see where you are after that. It could be one of those parts, but there's also the possibility the motherboard could be fried and the phone would basically be a total loss at that point so be aware of that.

The device page link at the upper right side of your question page has guides for those repairs should you decide to tackle them yourself. Each guide has a list of needed tools and parts you can buy right here on iFixit, but if you're on a budget you can easily find inexpensive components on sites like AliExpress, eBay and Amazon.

Good luck, and let us know how it all turns out for you.