My experience with errors like this is typically - the computer is right.
I this situations this means:
- the server does not know about the key you are using
- you changed the private ssh key to authenticate yourself
- and/or you removed the public ssh key from the authorized_keys on the server
there are more options, but for a start it would be good to check this
maybe you have executed ssh-keygen on your local machine on you overwrote your
please check that the matching public-key for the private-key you are using is in the
.ssh/authorized_keys in the users' userhome on the server you want to access.
please check and/or provide some verbose/log output - for eg.
ssh -v ... from the client