1. You can’t spell
The first thing to test is have you spelled the name of the package correctly? Package names are case sensitive in R.
2. You didn’t look in the right repository
Next, you should check to see if the package is available. Type
See also ?setRepositories.
To see which repositories R will look in for your package, and optionally select some additional ones. At the very least, you will usually want
CRAN to be selected, and
CRAN (extras) if you use Windows, and the
Bioc* repositories if you do any
[gen/prote/metabol/transcript]omics biological analyses.
To permanently change this, add a line like
setRepositories(ind = c(1:6, 8)) to your