How would reinstalling it be causing a problem to the charge?
I have no idea. When I read the OP post that suggested this option, I thought it was crazy too. But it worked for me, twice.

The battery itself is fine i'm thinking it's the charger..There's no other way to explain it
Could also be the motherboard. Have you checked the manufacturers support site for help?

And how much would a new charger cost normally?
Usually OEM chargers are expensive, but you may be able to find one on ebay/cl or perhaps buy an aftermarket. What is the make/model of the laptop?