First, do not forget the t ("puniroots").

Second, I gave in R the command: library(punitroots)

but R replied with:

there is no package called ‘punitroots’

Apparently something more must be done but I can't help you further. Search the internet.

Before installing "punitroots" package you need install "CADFtest" package from the CRAN repository because the latter is the dependency package. Since "punitroots" package is under R-Forge, you need to download the package in the zip form and install from the zip folder. I have downloaded both packages and they are working fine in my computer.

You can try directing to a specific repo, for example:

install.packages("punitroots", repos="http://R-Forge.R-project.org")

you may also try to install from a github directory:

library(devtools)

install_github('rforge/punitroots/pkg')

In both cases, there may be one or are several dependencies not correctly set as dependencies in the source code of the package, and you may need to install them manually using install.packages("xxx"). Look at thrown errors, if any, to see what may be missing.

Thanks Bo Pieter Johannes Andree for your suggestion. The command line you advised also works fine.

install.packages("punitroots", repos="http://R-Forge.R-project.org")