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Please see the official X‑Plane Support page for help.
I am not from Laminar Research; just a flight simmer from downunder.
Like you, I also have a disc version of XP11. The only way the disc version of XP11 and XP10 will run is with disc 1 installed in your DVD drive at all times. This is not like XP10 which has a USB dongle available as a substitute for disc 1. Some time back Laminar Research advised they have no intention of making the USB dongle available for XP11. If you don't have disc 1 inserted in the dvd drive XP11 will automatically revert to the demo version which is limited to a set location and has a time limit of use (10 minutes)
Neither XP10 or XP1 will accept any other disc as disc 1 has all of the encryptions installed to allow you to run a legal copy of X-Plane. So in making that statement disc 2 or any other of disc will allow you to run XP.
Considering your dog ate your disc 1, I suggest you contact Laminar Research direct at email@example.com with your problem In doing so you can make arrangements to acquire a replacement disc 1. I imagine you may be asked for a fee.
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