Airtel — invalid sim /no service

Address: Chennai, Tamil Nadu, 600083

Hi i have been a airtel prepaid sim for more than 10 years 2 year ago i have updated a 4 g sim too. But from today evening it self it doesn't work it shows as invalid sim (No service) when i contact the customer care through other mobile network they said there is no any issues at our side, and askes me to change the setting in mobile network though i have done as per their guidance my sim is in the same condition.
Kindy rectifie the issue aeap as i was my personal mobile and i used for all my account and everything.
Regards
Satheesh. S
Lvs. [protected]@yahoo.com