Hi @sakshamjha
Do you have the same problem when connecting to WiFi?
If so, since both the WiFi and the BT use the same antennas there may be a problem with the antenna connection (loose?) to the WiFi/BT card.
Here's the https://download.lenovo.com/consumer/mobiles_pub/v1415_g2_hmm.pdf|hardware maintenance manual] for the laptop.
Go to p.58 to view the procedure to remove the WiFi card.
You don't have to remove the card, just check that both the antenna cables are securely connected to it - see image on p.59.