Wordpress SSH / SFTP Access

Hi, there

I'm not sure what I've done wrong, but for some reason SFTP (note: not FTPS) is no longer working on my Wordpress blog. I type in the locations to the public and private keys, but it gives me this error: "Public and Private keys incorrect for [USERNAME]" where [USERNAME] is the user I'm logging in as.

I have disabled password logins to SSH, and enabling them has not worked either, resulting in an incorrect password error. It's very strange. This was working fine the last time I tried it, but no longer is. Perhaps my user doesn't have access to the .ssh directory? - If that's the case, how would I give it such access?

I have also tried logging in as root (and also permitting root login, as I had that disabled originally), and this also hasn't worked.

The keys are definitely, 100% correct, as I have copies on my local machine and they're identical.

I've tried chown and chmod, but to no avail.

Any ideas? Perhaps a guide to setting SSH up (I'm using libssh2) for Wordpress would be helpful. I cannot find the one I originally read online. I am running the latest version of Debian and Wordpress on Apache which is routed via Nginx.

Again, it used to work fine. The only thing that I can think of is when I deleted my user about a month ago and created it again from scratch after trying to limit SSH access to only the /srv/www/ directory.

Thanks in advance.