If your svn client suddenly starts complaining about something similar to
svn: OPTIONS of '...': SSL handshake failed: SSL error: A TLS warning alert has been received. (...)
The reason might be that the host in the URL (https://example.com/ => example.com) doesn’t match the ServerName setting in the SSL host for your web server. You might not have configured this, so for Apache add:
.. and restart the server. It might just work again!