How to map gene names to ensembl Ids in R
You can pull a full list of Ensembl gene IDs and MGI symbols from biomaRt in R. From there it should be easy enough to filter for the genes you want:

library(biomaRt)
hsapiens_genes &lt;- getBM(attributes = c("ensembl_gene_id", 
                                       "hgnc_symbol"),
                        mart = useMart("ensembl", dataset = "hsapiens_gene_ensembl"))


You do not find some genes in your example because you were not using the official gene name. For example CTGF is offocially called CCN2 and with this name you will find the appropriate Ensembl gene ID in the biomaRt table. This is why I personally prefer to use gene name that are like ENSG00000118523|CCN2 in my work. That way you always have a unique identifier (the Ensembl ID) that is unambiguous and you do not run into trouble that for one gene many more or less official gene names exist.