The first thing to do is write the most detailed and correct letter to the technical support of the service that provided you with the wallet and generated the key. Then, having already received an answer from them, it is worth following the instructions and not inventing some incomprehensible ways to solve the problem. Most often, technical support goes to a meeting in such situations. I myself lost my key, but thanks to normal communication with technical support and providing all the information that was asked of me, I got access to the wallet again. Everything is real, but without haste and panic.