If you can’t connect Mac and Windows computers
If you can’t connect Mac and Windows computers, make sure both computers are on the same network and the network connection is working. Here are some additional things to try.
Make sure your Mac is connected to the network. To check your connection, choose Apple menu
in the sidebar (you may need to scroll down). Your type of network connection is listed on the right. The indicator next to it should be green.If the computers are supposed to be in the same workgroup and on the same local network or subnetwork, make sure the workgroup name is exactly the same on both.
Make sure you typed the computer names and workgroup name correctly.
Make sure you typed the Mac user name and password correctly.
In some cases, you may need to reset the password for the account in Users & Groups settings. See Change User settings.
Make sure you typed the Windows user name and password correctly.
The password for the Windows user account you’re using may need to be changed on the Windows computer.
In some cases, the Windows computer may need to be restarted after the password is changed.
If you’re trying to connect to a shared folder on a Mac and see a message that the folder you specified isn’t valid, make sure you entered the information correctly. If the information is entered correctly, then check to see whether the Mac is in sleep mode.
If you don’t have access to one or both computers, contact the computer or network administrator for help.
Check Windows Help and Microsoft support services for more information about setting up file sharing on your Windows computer.