It is likely that a vital file on your PC has gone missing or it location has been lost.
From the Account Preparation menu in Troika Wealth Management, select the Show Other Settings at the bottom of the screen.
At the foot of the screen that opens you should see a message in red that says External.lst file on C:\TWW\Troika, length 194. If the message says file not found or length zero, please contact your IT department to check your Troika installation, or contact Support.