How does a pilot replace their logbook if it has been lost?
The best approach is to start a new logbook with totals that carry over from your latest FAA 8710 - in this case, it sounds like you will roll back to the hours from when you earned your private pilot certificate. There are some other options listed in FAA Order 8900.1, 5-172, but it's unlikely any of them will work for your situation (except, perhaps for "Receipts for aircraft rentals", if your FBO is still open and still has the records).

You can request a copy of your 8710 from the FAA, which I'm gonna quote here because that's the best way to not screw anything up:


  Airmen who have lost their logbooks or flight records may request copies of their files from the FAA [by sending this form] to the following:
  
  
    FAA Airmen Certification Branch, AFS-760
    P.O. Box 25082
    Oklahoma City, OK 73125
  
  
  or
  
  
    FAA Aeromedical Certification
    P.O. Box 25082
    Oklahoma City, OK 73125
  


Once you receive the copy, the first line in your new logbook should probably summarize all the totals from the 8710 (just like if it was a flight). The remarks would specify "time forward from 8710 dated DD/MM/YYY" or something to that effect.

Best of luck getting your records back!