From time to time we see Nintex installations that do not have any OOTB workflow templates. This is usually noticed straight away because the "Select a Template" dialog box is empty.
If you find that the "Select a Workflow Template" dialog box is empty then you should also check the "Workflow template Gallery".
You can browse the "Nintex Template Gallery" by browsing:
If everything is working fine then it should look something like this:
If you find that the "Nintex Template Gallery" is empty then you can resolve this issue by "Deactivating" and then "re-activating" the "Nintex Workflow 2007 Site Collection Feature.
Once you have deactivated and re-activated the feature, you should find that your Nintex Workflow templates are now available.