Ssh – Permission denied (publickey)

I'm unable to ssh into my ubuntu server (I used to be able to but haven't tried for a couple of months).

usually I use

ssh user@ipaddress

but I get the error Permission denied (publickey).

so I tried

ssh -o PubkeyAuthentication=no user@ipaddress

but I get the same error Permission denied (publickey).

the I tried

ssh -v user@ipaddress

OpenSSH_5.2p1, OpenSSL 0.9.8y 5 Feb 2013
debug1: Reading configuration data /etc/ssh_config
debug1: Connecting to ipaddress [ipaddress] port 22.
debug1: Connection established.
debug1: identity file /Users/my-mac/.ssh/identity type -1
debug1: identity file /Users/my-mac/.ssh/id_rsa type 1
debug1: identity file /Users/my-mac/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.0p1  Debian-3ubuntu1
debug1: match: OpenSSH_6.0p1 Debian-3ubuntu1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.2
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'ipaddress' is known and matches the RSA host key.
debug1: Found key in /Users/my-mac/.ssh/known_hosts:11
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /Users/my-mac/.ssh/id_rsa
debug1: Authentications that can continue: publickey
debug1: Trying private key: /Users/my-mac/.ssh/identity
debug1: Trying private key: /Users/my-mac/.ssh/id_dsa
debug1: No more authentication methods to try.
Permission denied (publickey).

I'm not sure what else to try to access my server.

p.s. here are the file perms

drwxr-xr-x   6 my-mac  staff   204  2 Oct 08:16 .
drwxr-xr-x+ 31 my-mac  staff  1054 21 Aug 07:35 ..
-rw-------   1 my-mac  staff  1743 12 Aug  2011 id_rsa
-rw-------   1 my-mac  staff   416 12 Aug  2011 id_rsa.pub
-rw-------   1 my-mac  staff  4390  2 Oct 08:16 known_hosts
-rw-------   1 my-mac  staff  4404  2 Oct 08:03 known_hosts.old