Accidentally closed a Terminal window

If you mean after the fact, no.

You can use the program "screen" to run a session, disconnect, and reconnect later.

man screen

for more info.

if you decided to go with the screen command, you may want to set up a
~/.screenrc file. You can work out you own. Or use the one at

http://www.softpanorama.org/Utilities/Screen/screenrc_examples.shtml

I just stumbled across this tutorial.

[LJDT: Taking Advantage of Screen|http://www.novell.com/communities/node/8560/ljdt-taking-advantage-screen ]

In most cases, when you close a window, any process running in that window (or, more technically, the shell) will terminate.

That's not always the case, but you usually have to go to extra lengths to make a process persist beyond the current shell session.

So the chances are that the process is no longer running anyway.

AFAIK, the screen suggestions will only work for a process that was launched via screen. You cannot attach to an arbitrary process.