how to recover my contacts from my old 2G SIM which has upgrated to 4G

[AC Question]

I have just upgraded my 2g airtel sim to 4g,but has no back up for contact.now i found that my my contacts lost. Pl,help me to recover my contact.

 

[B. Diddy]

Welcome to Android Central! What phone are you using? Were the contacts only saved to the SIM card? Try bringing it to your wireless store and see if they can retrieve the contacts and transfer them to the new phone.