Sorry to hear your parcel is missing - it is always very disappointing when it is an item you have waited a long time for, and can't easily be replaced. ☹️

Is the tracking information reporting it is definitely lost? If it was sent by Simple Delivery, you will automatically be refunded, but that is not much consolation when it is the item you wanted.

Some sellers won't use Evri because of their very poor reputation, but unless a seller chooses to exclude Evri from their Simple Delivery postage options, Evri is usually the default service.

In future, if it is an item you are particularly anxious to receive safely, it is worth checking with the seller before purchasing, and asking if they would be willing to temporarily exclude Evri, so you can have Royal Mail instead.