Edwin de Klerk

If a restart doesn't cure it, then I'd reset Trados Studio.  You could use this app for the reset and this will also explain what you will lose by carrying out a reset before you do it:

appstore.sdl.com/.../

But if you'd rather do this manually then rename this folder (just add _old to the end or something, it's not important what you rename it to) and restart Studio:

c:\Users\[USERNAME]\AppData\Roaming\SDL\SDL Trados Studio\Studio16

So the path would become this:

c:\Users\[USERNAME]\AppData\Roaming\SDL\SDL Trados Studio\Studio16_old

If you can't find this folder then you need to unhide your hidden files/folders:

www.howtogeek.com/.../