For Windows users, the TortoiseSVN Help has a comprehensive listing of questions asked for those starting out with Subversion.

Similarly for Linux users, the Subversion online book provides a troubleshooting guide for most common problems.

What you will find on this page, however, will be answers to those questions, perhaps not quite so frequently asked, usually because they are specific to our network, or our computers.

If there is nothing to help you here and the TortoiseSVN Help or online troubleshooting guide cannot help, please email your question to the Pagemasters.

General

The file I committed doesn't appear or hasn't updated

If you committed the file with a syntax error, it would stop the automatic update. Your file changes would, therefore, not appear on the live site.

You can check for errors at the Subversion background log file.

If this doesn't help, contact the pagemaster.

Windows

I want to roll back to a revision prior to the file I have just committed

If you are sure you have committed your file (i.e. svn revert doesn't work), then open up the Tortoise Help and search the Index for Rollback. The heading you are looking for is B4. Roll back revisions in the repository.
These instructions will help you retrieve your file.