since you acknowledged you were modifying
/etc/ssh/sshd_config over ssh, and you screwed up the file, and for some reason
sshd restarted, you're SOL, since i presume you /only/ have remote access.
if you have
cpanel or some other web interface that allows you to download/upload system files, edit system files, or even reset to default the system files, that would be your next place to look.
you could upload a new copy of
/etc/ssh/sshd_config, though i don't know how to guide you through a control panel interface, and then restart
sshd on the server, or if you can edit the files or restore to default to fix your errors.
beyond that, you will have to contact their support and ask that they reset the file
/etc/ssh/sshd_config and restart the ssh server for you.
to fix your problems, you will want to modify the file and undo the changes you did, and find any syntax errors. you can find syntax errors by running
/usr/bin/ssh -t which will check for correctness.
in another response, it sounds like you changed the default port, have you tried connecting to your host, specifying /that/ port in putty?