I think we need a bit more information to diagnose this problem:
(1) The shared folder is on Ubuntu and not Mint, correct?
(2) What OS is on the other machines that cannot access the share?
I had a shred folder set up and now the other local computers can not access.
(3) Is this a recent development - did the other lan member have access at one time and it just recently stopped?
(4) What is the exact error message you are receiving - if any.
(5) How did you share the folder - using "Simple Sharing" or "Classic Samba". The share definitions are in different locations:
Simple Sharing is defined in /var/lib/samba/usershares
Classic Samba is defined in etc/samba/smb.conf
You might want to do this just so we can see if something odd has happened to your config files:
Type testparm /etc/samba/smb.conf
This will do 2 things:
(1) It will do a check on the syntax and other checks on the content of
the smb.conf file itself
(2) The last step will be to output to the terminal the smb.conf file
itself without any comments ( the lines starting with "#" and ";" )
making it a lot smaller when you post to the forums