Loop Mobile — regarding mobile number activation

I had a number [protected] with loop mobile which was later ported to Airtel. I left the country for an intermediate period but the sim got deactivated abroad. I have been trying to activate the sim from march 2018 but I am unable to do it with airtel. The number is still not provided to anyone as it appears to be invalid when u call. I have the number linked with everything and it is highly impossible for me to change the number. I contacted airtel many times and they have been saying that the number no longer belongs to them. It has been given back to the original circle. However, loop mobile is no longer active so I would like to activate the number asap as it is causing me extreme distress