What happens if you run library("Rcmdr") now?
Rcmdr depends on many packages, and those packages themselves depend on many other packages. Ideally, install.packages() would correctly traverse this complex dependency tree, but for various reasons (including temporary inconsistencies between CRAN mirrors), that doesn’t always happen.
When things go sideways, the thing to pay attention to is what package or packages the console messages say are missing, then try to install those missing packages directly, then restart your R session (close R GUI and reopen it, and say “no” if it asks you if you want to save your workspace) and try loading Rcmdr again. It can take a few rounds of this to get everything installed.
You may also want to check out the Rcmdr installation notes, if you haven’t already.