Positive and negative contact's how laptop

[Wolfejp]

My power jack is worthless have to hardwire but have no idea which is positive or negative, need help.

 

[helpstar]

Isn´t it possible to replace the power jack?

Which laptop brand and model is it?

Have a look at your charger, there should be the correct symbol where minus and plus are. like:
https://upload.wikimedia.org/wikipedia/commons/6/68/AC_adaptor_polarity.png

In the picture on the left, plus is the inner contact and minus on the outer one