Sudo password is not working

Question

We had to do some configuration to our system in our company and they wanted to do these steps:

1. sudo vi /etc/pam_radius_auth.conf

2. Add

   *****.com ***radius 3
   

3. Add auth sufficient pam_radius_auth.so localifdown to following files just above @include common-auth:

   /etc/pam.d/login
   /etc/pam.d/sshd
   /etc/pam.d/sudo
   

4. Add try_first_pass in /etc/pam.d/common-auth:

   auth [success=1 default=ignore] pam_unix.so nullok_secure
   try_first_pass
   

I did two mistakes, first I added the line they said (in step three) to last file and forgot to add it to two first file:

/etc/pam.d/login
/etc/pam.d/sshd

Second I added the whole line in step 4 to the end of the file instead of just concatenating to:

 auth [success=1 default=ignore] pam_unix.so nullok_secure

I can not sudo any more after I restarted my system. I need to modify those files and without sudo I don't know how I should do it. I tried the recovery mode in this link and no luck. In the recovery mode it prompts me for root password and none of the password is working. I still can login to my account but apparently my sudo user is mis configured. I appreciate any help.