Hover your mouse pointer over the Multiterm Desktop/ Trados Studio icon in your taskbar and wait for the miniature window to appear. Then right-click on it and select Maximize.
1. This can happen in a multi-screen environment if the product was opened and not closed on a screen that was removed. The application remains 'stuck' on the no longer existing screen
2. This also used to happen in a specific version of Multiterm Desktop 2019 (Build - 188.8.131.52471) if you minimized the software and closed it from the taskbar or task manager. The next time you launched it was still minimized in the taskbar.
This was raised in the past with development as a defect (CRQ-11258) and was fixed in MultiTerm 2019 CU04 (Build 184.108.40.206976, Released on 13 May 2019)