Hi Bella,
I really wish I had more experience in PHP programming as I'm sure this can be corrected. One needs to know the internal workings of the application more though. I really think if you had the right person helping you it should be possible to restore the ID numbers back to their original values (would probably initially need to remove all sessions which would force everyone to remember their password or get it sent to them again) but surely it can be done.
Best of luck and I hope you get it fixed back to how it was.
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