Hi @akashpadmukh
Check that the laptop charger has 19.5V DC on the charger cable's output plug, just in case it's a faulty charger/charger cable.
If the charger is OK then there may be a problem with the [https://www.ebay.com.au/itm/114382694021|DC-In jack] in the laptop. (supplier example only)
What can happen is that sometimes the inner connector of the jack, breaks internally and opens the +ve power supply path between the charger and the motherboard. This means that the motherboard receives no power and also the battery can't be charged either.
You would need to open the laptop and check that there's continuity between the DC In jacks +ve and -ve input and the wires onthe plug that connect to the output side of the jack.
Here's the [https://dl.dell.com/topicspdf/vostro-15-3568-laptop_owners-manual_en-us.pdf|owner manual] for the laptop.
Go to p.37 to view the procedure to remove/replace the power connector port (aka DC-In jack) so that you can gain access to the jack cable and unplug it from the motherboard so that you can test the jack with a meter.
If the jack is faulty it cannot be repaired, it has to be replaced. Search online for ''Dell fwgmm'' to find suppliers that suit you best.