Assuming Moneydance has installed Moneydance.exe can be found at C:/Program Files/Moneydance.
What syncing method were you using, Dropbox Folder or Connection?
As you were syncing by Dropbox which was your Primary computer, the computer you set to sync under FILE – SYNCING? Your second computer is the one you can’t change the syncing method under FILE – SYNCING. If your windows computer was your primary computer do you have a backup or a copy of your data set? If not, I can post a method to convert your second computer data set into a primary data set. If your Mac was your primary computer you can just sync your windows computer by using FILE – NEW – OPEN SYNCED FILE.