what is it doing? Is it floating? sitting on the bottom? in its shell, hanging out of the shell?
What are your water parameters? What are you feeding?
They can go inactive for several days and its still considered normal. Have you removed it and given it a sniff? When they are dead they have a VERY strong smell.
It is sitting on a rock on the bottom. I nudged it 2 days ago and it seemed afixed and I have not tried to move it since. The first day of inactivity there was a vent tube sticking out, but not anymore. I can't see it very well but the trapdoor seems closed.
Tank has been running over 6 months now. Water params are: ph 6.8, ammonia 0, Nitrites 0, don't have a nitrate test. Sand substrate. Planted with Rotalla Mcandra(sp?), Cryps and Java Fern.
Feeding is targeted to the fish and is varied between tetra crisps, omega 1, floating cichlid pellets, freeze dried brine shrimp and tubifex, sinking wafers and tetra micro crabs.
Filter is a Tom Rapids mini canister with a sponge over the intake and I run an airstone too.
Tempature kept around 80.
Fish in signature is current.
I would try target feeding it. It may not be getting enough to eat. I feed mine veggies (blanched and sunk with a chip clip) like green beans, zucchini, cucumber. Or something like algae wafers will work. I would not be too concerned or assume its dead yet. You could take it out of hte tank and sniff it, if its not stinky its not dead yet.