SVN: Where is my repository?
Easy answer is to run:
find / -name 'svnserve.conf'
svnserve.conf is a file that should reside in ${REPO}/conf.
Hard(er) answer is to find out if svn has a command to find out what URL you used for you initial checkout.
Edit: for a command line svn client, the way to find the repository root (the place you checked your code out from) would be running this inside your working copy:
svn info
The line in the output that reads 'Repository Root' shows the place you checked out from and thus to the place where you repo is.
Take some time to get familiar with svn on the command line here.
You have several different ways of accessing a subversion repository and finding the repository is different for each:
file://
This is the easiest. This means it's on the local machine where the path says it is.
svn://
This is using svnserve. Look for the process command line on the remote server and the path specified with the -r option is prepended to the path in the url to find the repository. If there is no -r option then the path in the url is the file system path.
svn+ssh://
This is svn over ssh. The path in the url is the filesystem location on the remote server.
http:// or https://
This is svn over http or https. You need to find the virtual host in your apache configuration and look for a <Location> section that matches your url path and look for a SVNPath or SVNParentPath config line. This will tell you the location of your subversion repository.
In Tortoise, choose the properties option. The top line will list the file path of the repository assuming it is direct file access.