are all workflows and forms affected by this problem? Did workflows and or forms work before or is it a new installation?
In my configuration the interactive service detection service is set to manual and workflows & forms are running good.
Nintex Workflow Start Service should be running though.
First, which version of Nintex Forms & Workflows are you running? 2013? 2016?
Can you check if the installed version is the latest Version available? If not I'd suggest you patch your installation before making any further changes.
Second, can you please open Nintex Workflow Management and open database setup there? Please ensure that you made all updates here.
If you see a greed update link next to the database version, hit it and check again after update has completed.
Third, could you open Central Administration and check the services running there via System Settings? Your services section should be shown as following:
If a service is not running, please try to start it from here.
Fourth, can you please ensure that you created a database for each, Nintex Workflow and Nintex Forms?
If you followed all steps, did anything help so far?