If you are reading this, you have a problem. I have a solution for some people and just relief for others. It all depends on your circumstances.
I may not give you the answer you want, but it will be the right answer.
If you left Mexico without "canceling" or turning in your vehicle permit and / or your tourist permit, you can't go back until you straighten things out.
I note this in my roadlogs, but so far, not one customer for this FAQ bought a roadlog from me.
All is not doom and gloom. There are ways to "get right with the law." It just takes time.
This FAQ is 5 pages of solid info.