All by itself? Or is your son three years old?
I think you'll find that it is. They sell them all over the place.
In my experience ethernet cables tend to go all the way from one end to the
other.
You don't.
You can even get short "extension" cables at some stores.
Right, and if it's the retaining clip that is broken; you
could epoxy the cable connection side to keep it on and
do without the tape.
All this talk of tape and epoxy, anyone would think that the home handyman's
most useful substance, hot glue, had never been invented.
Tape is too unreliable and epoxy is over-kill.
Hot glue rulez! It's removable should the need arise yet tenacious in it's
adherance. You could simply hot glue the wantonly damaged RJ45 connector
directly into the socket in the computer. As I think I mentioned, hot glue
is removable if need be. However, if the OP can afford the couple bucks
required, a joiner or extension cable (and hot glue) would indeed be the
better option.