Is there a way to recover from an accidental "svn revert"?

There is a solution... go to your recycle bin you'll find there the latest version of the deleted file. Tortoise "throwing" to the recycle bin every file that it revert.

Not really Subversion specific, but if you're working with Eclipse, you can try your luck in the local history.

Now, something a little bit more Subversion specific: if you don't want to make a branch for every change you do, you can keep a couple of trunk checked out locally (trunk-modif-1, trunk-modif-2...). Each "modification" is done on a separate tree and you only need to keep a list of which check out correspond to which modification.

Or you could use Git locally but I never tried it.

No, (absolutely) NO.

If you say to Subversion it should revert a file, all changes are gone by the wind.

Only your memory can get them back.

Exception: New files you had added, will only lose their status "added", but the file will remain in this directory, only status is unknown("?")

Platform / Software exception: Using TortoiseSVN on Windows, Revert first throws the files into Recycle Bin and then reverts them. You can dig into the Recycle Bin to recover the files.