R doesnt appear to be installed

Hi,
My laptop is powered by KDE neon (last KDE releases on Unbuntu 22.04). I had no problem with Rstudio until recently. For a week or so, when launching Rstudio, there is the following message: "R doesnt appear to be installed, please install R before using Rstudio". However, R is installed (which R returns /usr/bin/R). I cannot find how to fix this.
Thanks in advance

What happens if you try running R from the systems-level terminal?

Hi, actually, the problem is the installation of R since when I type R in the terminal, nothing happens. I have tried to delete and reinstall R version 4.1.2 (Ubuntu repositories) instead of V4.3 (R-cran repositories) but without any success. I have followed instructions posted on a French Ubuntu forum in order to delete previous version before installing the new one.

philippe@HP-elitebook:~$ which R
/usr/bin/R
philippe@HP-elitebook:~$ cd /usr/bin/R
bash: cd: /usr/bin/R: Not a directory

However, I think that R is installed.
Honestly, I have no clue to fix this...
Thanks for your reply

I believe R is the program not a directory.
Try
apt-get purge packagename or apt-get remove --purge packagename

What is the correct way to completely remove an application?

Yes , I was wrong,
with

Philippe@HP-elitebook:/usr/bin$

there is a file named R
but when I type R, nothing happens

Try the purge commands and a re-install? It might even bee a good idea to remove both R and RStudio and reinstall both.

No modification being root
Yes, I will do that tomorrow
Thanks !