Thank you to everyone, however I have found out the real solution. After replacing the power jack, my Lenovo was still not charging. After researching a little, I found out that my charger could be in need of replacement. So I bought a multi-meter/volt-meter and tested its voltage - it was meant to have an output of 20V but it outputted 0.2V. Then I bought a new charger and it worked! Thanks all once again!