If the disconnection was long enough so that the broker profiles indicator turned red, there is no option for MultiCharts to see what happens during disconnection.
If the disconnection was short and the indicator turned yellow and got back to green, it depends on the broker and if the broker can provide information about active orders active before the disconnection.
There is no option to enter a missing trade in the Order and Position Tracker manually, I'm afraid.
The only workaround here is deleting all the Order and Position Tracker History. If you’d like to do that, please close all the MultiCharts components and make sure no processes are left in TaskManager, go to C:\ProgramData\TS Support\MultiCharts64\TradingCenter\ and delete the Storage folder. Please note that this folder contains all the data from the Order and Position Tracker, so if you do need this data please do not delete it.