Installation problem: fatal error: rstan/rstaninc.hpp: No such file or directory

I was able to compile my package using rstan and rstantools. But now I get this message:
fatal error: rstan/rstaninc.hpp: No such file or directory
#include <rstan/rstaninc.hpp>

I am not sure what changes I made. I am running R.0.2 on
Platform: x86_64-pc-linux-gnu (64-bit).
The StanHeaders, rstan and rstantools all have the latest version!

Please tell me if I am making a stupid error somewhere!

Best wishes, Sujit

packageVersion(“StanHeaders”)
[1] ‘2.21.0.5’
packageVersion(“rstan”)
[1] ‘2.21.1’
packageVersion(“rstantools”)
[1] ‘2.1.1’

Possibly you just need to uninstall rstan and then reinstall it in a clean R session without autoloading any old stanfit objects.

Thanks for the advice Ben. I am glad that I was able to recompile partly following your advice! In addition I messed up my DESCRIPTION file so the header files got all over the place. Fun learning the hard way!
Best wishes, Sujit