If you are having this issue it is likely the dgrnwork.dll add-in has become disabled.
To enable it do the following:
In the word menu
go to Word options
Under the add-in menus on the left look for the NatSpeak Word add-in
Initially when I did this it was under the disabled application add-ins
Next to Manage COM add-ins at the bottom press Go…
Check on NatSpeak Word COM Add-ins
Press OK, close and reopen word and test dictation. If it is still not working go back in and check under add-ins that it is showing as an active application.
If it is still showing as disabled, manage, add-ins, Highligh NatSpeak Word AddIn and press Remove
Then press Add.
Browse to C:\Program Files (x86)\Nuance\NaturallySpeaking10\Program\dgnword.dll
Add and enable it. Close and reopen word and test again.