I have a 2001 DHS Deville Cadillac I lost power for interior lights cigarette lighter power locks and trunk I've tested all fuses and all good how can I get this fixed?

Yes that all sounds like BCM issues are going on.

Take out the owners manual from the glove box and read about the fuses under the specifications. It should have a diagram showing the fuse location and specifications.

is it a security feature because you lost power

check for blown fuse for cigar lighter, remove any debris from lighter sockets. reverse lamps possible broken wire at l/h trunk hinge

look at the large fuses in the under hood fuse box

Fuse number 18 20amp is for cigarette lighter.Its located in the trunk compartment fuse box. ------- If you need fuse box diagram showing the cigarette lighter fuse.Click the link below and see the diagram:---
http://technoanswers.blogspot.com/2011/10/where-is-cigarette-lighter-fuse-located.html ---------- This will help.Thanks.Helpmech.

their is another fuse box inside the car under the rear seat ck the fuses their.

Often the interior lights are looped on one circuit.
It only takes one bad connection to stop the 12v volts flowing. I would start with any connection that can be exposed to water or rust. Doors would be a good start.
Grab yourself a cheap multimeter and probe each connection (after removing the light bulb / lamp) for the presence of 12 volts DC.
If you have an electrical drawing use the 50/50 rule. ie check for power at the 50% point (halfway in the drawn circuit). If there is power at that point, check again at the next approximate 50% point ie downstream, continuing until you narrow down the area wit the problem. NOTE: If there is no power at the initial 50% point (the very first place you checked) work your way backwards (or upstream) in the circuit towards the fuse box, again using the same 50/50 rule.
If you are not confident, take it to a reputable automobile electrician.
Good luck,
Steve

check blown body and / or lighter fuses 20A

two relays were bad one for the interior light and cig lighter and the other for the headlights