My Laptop doesn't charge?!

Sounds like you have an internal motherboard issue. Could be the connector itself, but I would have a professional diagnose the problem.

Carefully examine the connector for physical damage, since you mentioned your sister has the same laptop, it would be helpful to compare it with their working laptop. If you see damage at the connector good news, you only need to replace the connector. It may require soldering though. If the connector looks completely fine, I would check with a multimeter to make sure that the connections have continuity. If they do, then it is most likely the charging IC on the motherboard, and those can be very tricky to source and replace.