Newest version un-synced 2 of my PC's Windows 10

I have 4 PC’s: 2 with Window’s 10, 2 on Windows 8. The 2 on Windows 10 have a version 7 something and this week (7-24-2017) no emails will show. Calendar is there but no emails coming or going and no emails in folders. The other 2 PC’s have a version 6 something and they work fine. My email is a HELP! I am a small business and my contract IT guys says I need to contact EM Client, but I’m getting very, very little help from them (one vague email). Any ideas from anybody?